Last update 4 August 2024
Please select a starting letter from the links below:
| ELR | Line name | Mileages | Datum | Notes |
|---|---|---|---|---|
| MAB | Mablethorpe Branch | 128.07 - 149.43 | Kings Cross | |
| MAC | Manvers Main Colliery Branch | 0.00 - 0.36 | Wath Junction | |
| MAC | Manchester and Cleethorpes Line | see separate portions | ||
| MAC1 | Dunford Bridge (LM/ER boundary) to Penistone | 22.20 - 28.37 | Manchester London Road | |
| MAC2 | Penistone to Deepcar | 29.13 - 33.20 | Manchester London Road via Woodhead | |
| MAC3 | Deepcar to Cleethorpes | 33.20 - 112.40 | Manchester London Road via Woodhead | |
| MAD | Malton to Driffield Line | 0.00 - 19.43 | Malton East Junction | |
| MAE | Maesycwmmer Branch/Fleur de Lis Branch | 10.11 - 10.69 | Taff Vale Extension Junction | |
| MAH | Manningtree and Harwich Line | 59.46 - 71.00 | Liverpool Street | |
| MAI | Maindee East Loop | 41.34 - 41.64 | Rotherwas Junction | |
| MAJ | Manchester and Allerton Junction Line | 6.11 - 34.05 | Liverpool Central | |
| MAK | Monkland and Kirkintilloch Branch | ?? - ?? | Line starts at Kirkintilloch Basin | |
| MAL | Malmesbury Branch | see separate portions | ||
| MAL1 | Dauntsey Junction to connection from Little Somerford Station | 87.63 - 91.18 | Paddington via Swindon and Dauntsey | |
| MAL2 | Little Somerford to Malmesbury | 89.66 - 93.35 | Paddington via Swindon and Brinkworth | 90.29 - 93.35 formerly 91.18 - 94.24 from Paddington via Swindon and Dauntsey. Line remiled 1933 |
| MAM | Maltby Colliery Branch | see separate portions | ||
| MAM1 | Maltby Colliery South Junction to Maltby Colliery | 8.67 - 9.30 | Brancliffe East Junction via Maltby Colliery Junction (reverse) | Later definition |
| MAM1 | Maltby Colliery Branch Junction to mileage change | 9.26 - 9.62 | Brancliffe East Junction | Former definition |
| MAM2 | Maltby Colliery South Junction to Maltby Colliery Bunker | 0.00 - 0.43 | Maltby Colliery Junction | |
| MAN | Mangotsfield South Loop | Now MAP | ||
| MAN | Manton Colliery Branch (Worksop) | see separate portions | ||
| MAN1 | Manton Colliery | 0.00 - 0.15 | Junction with MAN2 | |
| MAN2 | Manton Colliery Branch | 58.54 - 59.01 | Manchester London Road via Woodhead | |
| MAP | Mangotsfield South Loop | 0.00 - 0.33 | Mangotsfield Station Junction | Formerly MAN |
| MAR | Marefield to Leicester Line | 0.00 - 10.14 | Marefield Junction South | |
| MAS | Manchester and Sheffield Line | 153.73 - 174.01 | St Pancras via Leicester and Toton | |
| MAT | Mold and Tryddyn Branch | see separate portions | ||
| MAT1 | Mold to Llanfynydd | 0.00 - 5.37 | Mold & Tryddyn Junction | |
| MAT2 | Wrexham & Minera Extension Line | 0.00 - 2.67 | Brymbo Junction | |
| MAU | Mauldslie Branch | 0.00 - 1.22 | Mauldlie Branch Junction | Off Law Junction to Shawfield Colliery Branch |
| MAV | Menstrie to Alve Branch | 1.73 - 3.45 | Cambus | Or from 2.12 |
| MAX | Maxwelltown Branch | 0.24 - 3.06 | Dumfries | |
| MAY | Mayfield Branch | 0.00 - 1.37 | Mayfield Branch Junction | It appears that this should be the Manchester Mayfield goods station branch |
| MBA | Marsh Barton Estate Branch | 0.00 - 0.22/ 0.24 - 0.46 | Marsh Barton Junction/Exeter Railway Junction via Marsh Barton Junction (reverse and reverse count) | Formerly MBE |
| MBB | Musselburgh Branch | 4.54 - 6.03 | Edinburgh Waverley | |
| MBD | Melton to Bottesford Branch | 20.28 - 34.46 | Welham Junction | |
| MBE | Marsh Barton Estate Branch | Now MBA | ||
| MBE | Moor Row and Birksbridge Line | 2.14 - 3.49 | Mire House Junction | |
| MBH | Masham Branch | 0.00 - 7.45 | Melmerby Junction | |
| MBJ | Moorbridge Junction to Bulwell North Junction (Bulwell Connecting Line) | ?? - ?? | ||
| MBL | Mangotsfield to Bath Line | 124.46 - 134.60 | Derby | |
| MBN | Masborough North Curve | 163.07 - 163.70 | St Pancras | unable to identify at present |
| MBO | Marlborough Branch | 70.12 - 75.58 | Paddington | |
| MBT | Melton and Bottesford Line | 20.33 - 21.20 | Welham Junction | |
| MBW | Middlesbrough and Whitby Line | see separate portions | ||
| MBW1 | Guisborough Junction to Battersby Junction | 0.00 - 10.49 | Guisborough Junction | |
| MBW2 | Battersby Junction to Grosmont Junction | 11.61 - 29.66 | Picton | |
| MBW3 | Grosmont Junction to Whitby | 24.44 - 30.62 | Rillington Junction | |
| MBY | Moss Bay Branch | see separate portions | ||
| MBY1 | Moss Bay Branch | 0.00 - 1.43 | Harrington Junction | Moss Bay branch ( South) |
| MBY2 | Derwent Works Branch | 0.00 - 0.48 | Branch junction | Moss Bay branch (North) |
| MCB | Markham Colliery Branch | 6.77 - 7.02 | Pleasley Colliery West Junction via Markham Colliery Junction (reverse direction and count) | |
| MCC | Mansfield Colliery South | 0.00 - 1.00 | Datum unknown: presumably branch junction | |
| MCG | Maryport and Carlisle Goods Lines | 0.00 - 0.41 | Currock Junction | |
| MCH | Macclesfield and Cheadle Hulme Line | 0.00 - 9.37 | Cheadle Hulme Junction | |
| MCJ | Marylebone to Claydon L&NE Junction | see separate portions | ||
| MCJ1 | Marylebone and Harrow Line | 197.05 - 205.78 | Manchester London Road | |
| MCJ2 | Metropolitan & GC Joint Line (Amersham to Verney Junction) | 9.13 - 50.57 | Baker Street | 9.13 - 25.21 LUL property |
| MCJ3 | Great Central Main Line (Annesley to Quainton Road via Calvert Junction) | 69.59 - 161.50 | Manchester London Road | |
| MCJ4 | Claydon Loop (Calvert Junction to Claydon L&NE Junction) | 0.00 - 0.41 | Calvert Junction | |
| MCJ5 | unknown | Manchester London Road | ||
| MCL | Moorgate to Carlton Junction Line (Midland City Line) | 0.00 - 4.06 | Moorgate | |
| MCO | Manners Colliery Branch | 0.00 - 0.59 | Manners Colliery Branch Junction | |
| MCS | Margam Cripple and Holding Sidings | 198.58 - 199.32 | Paddington via Stroud | |
| MCY | Mosside Colliery Branch | 0.00 - 0.61 | Mosside Colliery Siding, Bathgate Upper | Remainder of branch RCH |
| MDB | Maryport Dock Branch | 0.00 - 0.64 | Docks Branch Junction | |
| MDC | Middlewood Curve | 0.00 - 0.32 | Middlewood High Level Junction | |
| MDE | Mossend East Curve | 0.00 - 0.31 | Mossend South Junction | |
| MDH | Mold to Denbigh Line | see separate portions | ||
| MDH1 | Pen-Y-Ffordd Connecting Line to Chester to Mold Branch | 0.00 - 0.31 | Pen-Y-Ffordd Junction | Formerly PSS1 |
| MDH2 | Mold to Denbigh | 0.00 - 14.74 | Mold | |
| MDI | Moor Lane Junction to Marsh (Ditton Brook Iron Works) Branch | 0.00 - 1.42 | Moor Lane Junction | |
| MDL | Manchester Diggle and Leeds Line | see separate portions | ||
| MDL1 | Thornhill LNW Junction to Holbeck East Junction | 32.17 - 42.03 | Manchester Victoria via Huddersfield | |
| MDL2 | Holbeck East Junction to Whitehall West Junction | 42.03 - 42.25 | Manchester Victoria via Huddersfield | Note that the 1967 rebuilding at Leeds makes it difficult to give exact definitions for this line |
| MDN | Mossend North Curve | -0.06 - 0.40 | Mossend North Junction | |
| MDNX | Mossend North Junction | 0.00 - 0.06 | Mossend North Junction | Not in GEOGIS but present in a structure maintenance system |
| MDT | Maiden Lane Depot Line | 4.33 - 4.66 | Broad Street | |
| MDV | Murton And Durham Elvet Line | 0.00 - 8.13 | Murton Junction | |
| MDW | Mossend West Curve | 91.08 - 91.50 | Carlisle | |
| MDY | Maerdy Branch/Rhondda Fach Branch | 16.13 - 22.62 | Cardiff Bute Road | |
| MDZ | Marsh Depot Goods Branch/St Philips Marsh Goods Branch | 117.58 - 118.12 | Paddington via Box | |
| MEB | Moorgate Branch | see separate portions | ||
| MEB1 | Open portion | 0.00 - 3.37 | Moorgate | |
| MEB2 | Closed portion | ≈2.60 - 3.34 | Moorgate | |
| MED | Mile End (Devonshire St) Sidings | 1.59 - 2.02 | Liverpool Street | |
| MEE | Medbourne Branch | 0.00 - 3.25 | Drayton Junction | |
| MEG | Merthyr Goods Branch | Now MRG | ||
| MEG | Marsh East Junction: Grimsby Line Curve | 0.00 - 0.14 | Marsh East Junction | |
| MEL | Meon Valley Line | 50.22 - 72.40 | Waterloo via Wimbledon, Guildford (reverse) and Tongham | |
| MEN | Muirhouse South Junction to Strathbungo Junction (Glasgow Central) | see separate portions | ||
| MEN1 | Muirhouse Central Junction to Eglinton Street Junction | 0.19 - 0.70 | Muirhouse South Junction | |
| MEN2 | Muirhouse South Junction to Muirhouse Central Junction | 0.00 - 0.19 | Muirhouse South Junction | |
| MEP | Methley and Pontefract Line | 59.03 - 61.13 | Manchester Victoria via Rochdale, Wakefield Kirkgate and Pontefract Monkhill (reverse) | |
| MER | Merthyr Branch | 0.00 - 6.22 | Gelli Tarw Junction | 5.70 - 6.22 now 24.19 - 24.51 in CAM |
| MEW | Methley Junction to Whitwood Junction Curve (Castleford) | See MEW2 | ||
| MEW | Methley Junction to Whitwood Junction Curve (Castleford) | see separate portions | ||
| MEW1 | Methley Junction | 1.12 - 1.16 | Whitwood Junction | |
| MEW2 | Methley Junction to Whitwood Junction | 0.00 - 1.12 | Whitwood Junction | Originally MEW |
| MEX | Merthyr Extension Line | 18.16 - 19.33 | Abergavenny Junction | |
| MEY | Mellis to Eye Line | 0.00 - 2.73/ 91.33 - 94.26 | Liverpool Street | |
| MEZ | Merthyr Low Level Loop | 0.00 - 0.19 | Ynysfach Loop Junction | |
| MFB | Maud to Fraserburgh Branch | 31.03 - 47.23 | Aberdeen | |
| MFD | Mansfield Line | see separate portions | ||
| MFD1 | Kirkby South Junction to Mansfield Colliery end on junction with CEM | 0.00 - 6.32 | Kirkby South Junction | |
| MFD2 | Mansfield South Junction to Rolleston Junction | 139.68 - 154.47 | St Pancras via Corby and Newstead | |
| MFD3 | Mansfield Colliery Branch | 142.22 - 144.06 | St Pancras via Corby and Newstead | |
| MFN | Milfraen Branch | 2.07 - 2.52 | Brynmawr | Waenavon Station to Milfraen Colliery |
| MGB | Monkseaton Goods Branch | ?? - ?? | ||
| MGE | Milngavie Branch | 6.19 - 9.35 | Glasgow Queen Street High Level via Maryhill | |
| MGS | Meikleriggs Branch | 0.00 - 0.60 | Meikleriggs Branch Junction | South of Paisley, Chain Road, Caledonian Railway |
| MGW | Milford Curve | 6.12 - 7.65 | Selby South Junction | |
| MGY | Middlesbrough Goods Yard | 0.00 - ≈1.34 | Newport East Junction | |
| MGZ | Gilbertsons Branch | 7.51 - 7.66 | Swansea St Thomas Station | |
| MHB | Hadfields Branch | 0.00 - 0.28 | Hadfield's Branch Junction | On Sheffield District Railway between West Tinsley and Brightside Junction |
| MHE | Millerhill Junction to Millerhill Yard Junction Line | 0.50 - 0.71 | ||
| MHH | Morecambe and Heysham Branch | 0.00 - 4.25 | Morecambe Junction | |
| MHL | Millerhill Branch | see separate portions | ||
| MHL1 | Wanton Walls to Monktonhall Junction | 5.60 - 6.12 | Haymarket Central Junction | Millerhill West Junction to Millerhill South Junction |
| MHL2 | Millerhill South Junction to Wanton Walls | 0.28 - 1.40 | Millerhill South Junction | |
| MHL3 | Millerhill East Junction to Millerhill Yard | 0.00 - 0.75 | Millerhill East Junction | |
| MHL4 | Millerhill EMU depot | 0.00 - 0.49 | Newcraighall East Junction | |
| MHS | Mirehouse and Sellafield Line | 0.00 - 9.44 | Mire House Junction | |
| MHY | Millerhill Yard Lines | 6.30 - 7.08 | Haymarket Central Junction | |
| MIA | Manchester International Airport Rail Link Line | 0.00 - 1.51 | Manchester Airport Station | |
| MIA2 | unknown | 0.00 - 3.22 | unknown | Not in GEOGIS but present in a structure maintenance system |
| MIB | Montrose to Inverbervie Branch | 30.69 - 43.10 | Dundee Tay Bridge | |
| MID | Middleton Branch | 5.19 - 6.21 | Manchester Victoria | |
| MIH | Mirfield to Huddersfield Line | 190.21 - 194.58/ 0.00 - 4.37 | St Pancras/Mirfield Junction | |
| MII | Mistley Incline | 0.00 - 0.60 | Mistley Junction | |
| MIK | Micklehurst Line | 8.04 - 14.69 | Manchester Victoria | |
| MIL | Milford Haven Branch/Old Milford Branch | 280.70 - 284.71 | Paddington via Stroud | |
| MIN | Minehead Branch | 164.60 - 187.76 | Paddington via Box | |
| MIN1 | Minehead Branch Turning Triangle | 165.20 - 165.42 | Paddington via Box | |
| MIR | Mersey Loop Line | see separate portions | ||
| MIR1 | Mann Island Junction to Mann Island Junction (Liverpool Loop Line) | 0.00 - 2.21 | Mann Island Junction via Moorfields | |
| MIR2 | Mann Island Junction to Rock Ferry Station | 0.69 - 3.46 | Liverpool Central Low Level | |
| MIS | Millbrook to Southampton Western Docks Branch | 79.78 - 81.59 | Waterloo | |
| MIS | Minsterley Branch | ?? - 5.50 - ?? | Shropshire | |
| MIT | Middleton Towers Branch (Kings Lynn) | 0.22 - 3.44 | Kings Lynn Junction | Line runs to Dereham as MTD |
| MJB | Bude Branch | 199.78 - 228.25 | Waterloo | |
| MJD | Marsh Junction Depot (Down Side) | 0.21 - 0.44 | North Somerset Junction | |
| MJI | Madeley Junction to Ironbridge Line | see separate portions | ||
| MJI1 | Madeley Junction to Lightmoor Junction | 156.19 - 160.16 | Paddington via Oxford and Birmingham Snow Hill | |
| MJI2 | Ketley Junction to Ironbridge via Lightmoor Junction | 160.01 - 166.63 | Paddington via Didcot, Charlbury and Buildwas East Junction (reverse) | |
| MJR | Morlais Junction to Rhydycar Junction | 18.75 - 23.56 | Brecon | |
| MJS | Melbourne Junction and Sinfin Branch | see separate portions | ||
| MJS1 | Melbourne Junction to Chellaston East Junction | 127.27 - 131.15 | St Pancras via Trent Junction, Sheet Stores Junction, Chellaston East Junction and Melbourne Junction | |
| MJS2 | Ashby-de-la-Zouch to Chellaston East Junction | 0.00 - 10.72 | Ashby-de-la-Zouch | |
| MJT | Mansfield Junction to Trowell Junction Line | see separate portions | ||
| MJT1 | Mansfield Junction to Radford Junction | 124.22 - 125.56 | St Pancras via Corby | |
| MJT2 | Radford Junction to Trowell Junction | 125.56 - 130.56 | St Pancras via Corby | |
| MJU | Marsh Junction Depot (Up Side) | 0.17 - 0.64 | North Somerset Junction | |
| MJW | Mitcham Junction to Wimbledon Line | 0.00 - 2.78 | Wimbledon | |
| MKB | Monk Bretton Branch | see separate portions | ||
| MKB1 | Cudworth North Junction to Cudworth West Junction | 0.00 - 0.34 | Cudworth West Junction | |
| MKB2 | Cudworth West Junction to Monk Bretton | 175.72 - 176.38 | St Pancras via Leicester, Toton and Barrow Hill | |
| MKK | Muirkirk Branch | 47.56 - 58.11 | Bridge Street Junction via Dalry | |
| MKT | Market Drayton Branch | 161.67 - 188.66 | Paddington via Didcot | |
| MLA | Maryhill Park Junction to Anniesland Line | 4.62 - 5.51 | High Street via Hyndland | original measure |
| MLA | Maryhill Park Junction to Anniesland Line | 0.00 - 0.73 | Maryhill Park Junction | current measure |
| MLD | Mouldron Branch | 0.00 - ?? | branch junction | |
| MLE | Millerhill East Curve | 0.09 - 0.28 | Millerhill Yard ?? | |
| MLF | Manuel Fork | 0.00 - 0.58 | Almond Junction | |
| MLG | Mallaig Line | see separate portions | ||
| MLG1 | Fort William Junction to Banavie Junction | -0.10 - 1.27 | Fort William Junction | |
| MLG2 | Banavie Junction to Mallaig | 0.00 - 39.39 | Banavie Junction | |
| MLK | Mawcarse to Ladybank (Fife and Kinross) Branch | 0.00 - 15.00 | Kinross | |
| MLL | Moss Lane Junction to Lostock Hall Engine Shed Junction (Walton to Preston) Line | 24.63 - 25.36 | Liverpool Exchange | |
| MLN | Hackney Yard | 213.24 - 213.70 | Paddington via Box | |
| MLN | Main Line (Paddington to Penzance via Bath) | see separate portions | ||
| MLN1 | Paddington to North Road Junction | 0.00 - 246.29 | Paddington via Box | |
| MLN2 | Cornwall Loop Junction to St Germans | 247.28 - 256.38 | Paddington via Box and Plymouth Millbay (reverse) | |
| MLN3 | St Germans to mileage change point east of Chacewater | 256.40 - 305.65 | Paddington via Box and Plymouth Millbay (reverse) | |
| MLN4 | Mileage change point east of Chacewater to Penzance | 305.67 - 326.50 | Paddington via Box and Plymouth Millbay (reverse) | |
| MLN5 | Plymouth North Road to Millbay station | 246.08 - 246.64 | Paddington | 246.64 (Millbay station) - 247.22 doubled |
| MLN6 | Bristol Temple Meads Old Station | 118.16 - 118.39 | Paddington | |
| MLN7 | Plymouth North Road west side of triangle | 247.22 - 247.42 | Paddington via Box and Plymouth Millbay (reverse) | |
| MLP | Middlemuir Loop | 0.00 - 0.33 | Woodley junction | |
| MLS | Margam Loco and Sorting Sidings | 198.34 - 199.30 | Paddington via Stroud | |
| MLT | Moat Lane Junction to Talyllyn | 52.18 - 108.27 | Whitchurch Cambrian Junction via Oswestry | |
| MLY | Millerhill Yard | 0.20 - 0.52 ?? | Millerhill East Junction ?? | Possibly 5.21 - 5.53 from Edinburgh Waverley |
| MMB | Mynydd Mawr Branch/Llanelly & Mynydd Mawr Line | 0.00 - 12.35/ 0.23 - 12.01 | Mynydd Mawr Stages/Llanelly Low Level Junction | |
| MMC | Markham Main Colliery Branch | 0.00 - 0.61 | Markham Colliery Junction | |
| MMH | Middlesbrough Marsh Line | see separate portions | ||
| MMH1 | Middlesbrough Marsh Branch | 0.00 - 0.56 | Marsh Branch Junction | |
| MMH2 | Middlesbrough Marsh Branch And Old Town Branch Loop | 0.41 - 1.16 | Marsh Branch Junction | |
| MML | Mynydd Mawr Loop | 0.00 - 0.23 | Llanelly Low Level Junction | |
| MMP | March Motive Power Depot | 86.19 - 86.45 | Liverpool Street via Clapton and Ely | |
| MMR | March to Magdalen Road Line | ?? - ?? | Duplicates WIG? | |
| MMW | Moira West Junction to Shackerstone | Now AMS | ||
| MMZ | Maes-y-Marchog Branch | 0.00 - 1.59 | Onllywn Junction | |
| MNB | Methven Branch | 4.61 - 6.03 | Almond Valley Junction | |
| MNC | Monckton Main Colliery Branch | 0.00 - 1.03 | Cudworth (Yard) North Junction | A new line opened from this box at 51.29 on Hull & Barnsley Line on 1 June 1958 |
| MNG | Morningside Branch | 0.00 - 13.44 | Polkemmet Junction | |
| MNL | Mid Notts Joint Line | 0.00 - 7.72 | Farnsfield Junction | |
| MOA | Mountain Ash deviation | 0.00 - 0.38 | south end of deviation | |
| MOB | Moretonhampstead Branch | 0.14 - 12.34 | Newton Abbot | |
| MOD | MOD Chilmark Branch | 91.72 - 93.41 ± private sidings | Waterloo | |
| MOF | Muir of Ord to Fortrose (Black Isle) Branch | 0.12 - 13.45 | Muir of Ord | |
| MOL | Motherwell Old Line | ?? - ?? | Location uncertain | |
| MON | Monkland Branch | ?? - ?? | See also MLP, CME, MAK | |
| MOO | Moorfields Branch | 0.00 - 0.37 | Moorfields Junction | |
| MOR | Morriston Branch | 0.00 - 3.29 | Haford Junction | Formerly 0.00 - 3.21; junction moved and line remiled 1964 |
| MOS | Mossend Branch | ?? - ?? | ||
| MOT | Moffat Branch (Beatock to Moffat) | ?? - ?? | ||
| MOU | Mountain Branch/Crosshands Branch | 0.00 - 4.03 | Mountain Branch Junction | |
| MOW | Mowbray Branch | 0.00 - 0.58 | Eskett Junction | |
| MPC | Motspur Park and Chessington Branch | 10.11 - 14.32 | Waterloo | |
| MPM | Moffat Paper Mill Branch | 0.00 - 1.23 | Springbank Quarry Junction, Clarkston (Lanark) | |
| MPR | Miles Platting and Rochdale Line | see separate portions | ||
| MPR1 | Miles Platting to Thorpes Bridge Junction | 1.30 - 2.17 | Manchester Victoria | |
| MPR2 | Thorpes Bridge Junction to Oldham Werneth Junction | 2.14 - 6.15 | Manchester Victoria | |
| MPR3 | Oldham Werneth Junction to Rochdale | 6.15 - 14.27 | Manchester Victoria via Dean Lane | |
| MPR4 | Middleton Junction to Oldham Werneth Junction | 5.24 - 6.68 | Manchester Victoria via Moston | |
| MPT | Merton Park to Tooting Line | 3.56 - 5.51 | Streatham South Junction via Wimbledon/Merton Park | |
| MRB | Milner Royd Junction and Bradford Interchange Line | 29.20 - 40.41 | Manchester Victoria via Rochdale | |
| MRC | Moor Row Junction to Corkickle Branch | 72.72 - 73.73 | Carnforth | Parallels CBC1 |
| MRG | Merthyr Goods Branch | 23.62 - 24.28 | Cardiff Bute Road | Formerly MEG |
| MRH | Macclesfield and Rose Hill Marple Branch | 0.00 - 11.02 | Macclesfield | |
| MRJ | Margam Moors Junction | 198.64 - 199.20 | Paddington via Stroud | |
| MRL | Maryhill Line (Westerton to Cowlairs West Junction) | see separate portions | ||
| MRL1 | Maryhill Park Junction to Cowlairs West Junction | 5.51 - 8.26 | High Street via Hyndland | |
| MRL2 | Maryhill Park Junction to Knightswood North Junction | 4.40 - 5.67 | Glasgow Queen Street High Level | |
| MSB | Murrow to Sutton Bridge Line | ?? - 14.61 - 26.18 - ?? | Duplicates PMY1? | |
| MSC | Masborough South Curve | 161.50 - 161.72 | St Pancras via Chesterfield and Treeton | |
| MSD | Manchester South District Railway | see separate portions | ||
| MSD1 | Heaton Mersey Station Junction to Heaton Mersey East Junction | 0.00 - 0.66 | Heaton Mersey Station Junction | |
| MSD2 | Heaton Mersey Station Junction to Chorlton Junction | 182.22 - 185.54 | St Pancras | |
| MSG | March and Spalding Line | see separate portions | ||
| MSG1 | Whitemoor Junction to Grassmoor Junction | 86.20 - 87.05 | Liverpool Street via Clapton and Ely | |
| MSG2 | Grassmoor Junction to former Regional Boundary | 25.63 - 26.63 | Huntingdon South Junction via St Ives (reverse) | |
| MSG3 | Former Regional boundary to Spalding | 26.63 - 44.07 | Huntingdon South Junction via St Ives (reverse) | |
| MSK | Misk Branch | 0.00 - 0.57 | Misk Branch Junction | |
| MSL | Birmingham Moor Street Line | 128.53 - 128.70 | Paddington via Didcot | |
| MSM | Morecambe South Junction and Morecambe Branch | 0.00 - 2.50 | Morecambe South Junction | |
| MSN | Marston Branches | see separate portions | ||
| MSN1 | Marston Branch | 0.00 - 1.66 | Northwich East Junction | Also known as Salt Branch No 1 |
| MSN2 | Marston Branch No 2 | 0.00 - 0.46 | Wincham Lane Junction | Also known as Salt Branch No 2 |
| MSN3 | Marston Branch No 3 | 0.00 - 0.70 | Northwich Central Junction | Also known as Salt Branch No 3 |
| MSR | Mossend Spur | ?? - ?? | ||
| MSS | Misson Branch | 147.67 - 155.48/ 0.00 - 7.61 | Haxey | |
| MST | Mosley Street Branch | 0.00 - 0.28 | Mosley Street Branch Junction | |
| MSV | Morriston and Swansea Vale Branch | 1.34 - 6.23 | Swansea St Thomas Station | |
| MSW | Minster South to Minster West Curve | 81.67 - 82.21 | Charing Cross via Chelsfield and Canterbury West | |
| MSZ | Moreton & Shipston Tramway/Shipston-On-Stour Branch | 91.49 - 100.56 | Paddington via Didcot and Charlbury | |
| MTA | Merthyr Tredegar and Abergavenny Line | 0.00 - 18.16 | Abergavenny Junction | 13.74 - 15.31 = part RRZ 25.26 - 26.63 ex Cardiff East Dock |
| MTD | Middleton Towers to Dereham line | 3.44 - ≈26.44 | King's Lynn Junction | Continuation of MIT |
| MTE | Menstrie Branch (Stirling) | 0.00 - 3.45 | Cambus | |
| MTJ | Mickle Trafford Junctions | see separate portions | ||
| MTJ1 | Up/Down Warrington Line | 0.00 - 0.15 | Mickle Trafford Junction | |
| MTJ2 | Up/Down Passenger Line | 35.24 - 35.41 | Manchester Central | |
| MTK | Melmerby And Thirsk Line | 31.43 - 37.47 | Leeds Wortley Junction via Pannal Junction and Starbeck avoiding Harrogate | |
| MTL | Methil Docks Branch (Glenrothes) | see separate portions | ||
| MTL1 | Thornton North Junction to East Fife Central Junction | 0.11 - 4.65/ 0.11 - 6.01 | Thornton North Junction | |
| MTL2 | East Fife Central Junction to Methil Boundary | 5.09 - 7.34 | Thornton West Junction via Wemyss Castle | |
| MTM | Meltham Branch | 0.00 - 3.43/ 1.39 - 5.02 | Meltham Junction/Huddersfield station | |
| MTN | Morton Branch | 0.00 - 1.68 | Morton Branch Junction | |
| MTY | Minsterley Branch | 0.00 - 4.53 | Cruckmeole Junction | |
| MUP | March Up and Down Yards | 85.30 - 85.66 | Liverpool Street via Clapton and Ely | |
| MVB | Manchester Victoria and Bury Line | see separate portions | ||
| MVB1 | Manchester Victoria to Queens Road Junction | 0.00 - 1.38 | Manchester Victoria via Collyhurst Tunnel | |
| MVB2 | Queens Road Junction to Radcliffe North Junction | 1.21 - 7.65 | Manchester Victoria via Cheetham Hill Junction | |
| MVB3 | Radcliffe North Junction to Bury Loco Junction | 7.65 - 8.63 | Manchester Victoria via Cheetham Hill Junction | |
| MVB4 | Bury Loco Junction to Bury Loop Junction | 8.63 - 9.73 | Manchester Victoria via Cheetham Hill Junction | |
| MVC | Manvers Main Colliery Branch (Midland) | 0.00 - 0.04 | Manvers Main Colliery Junction | also listed 169.08 - 169.10 |
| MVE | Manchester Victoria and Euxton Junction Line | see separate portions | ||
| MVE1 | Manchester Victoria to Bolton | 0.00 - 10.40 | Manchester Victoria | |
| MVE2 | Bolton to Euxton Junction | 10.40 - 25.31 | Manchester Victoria | |
| MVL | Manchester Victoria and Huddersfield Line | see separate portions | ||
| MVL1 | Miles Platting to Stalybridge Junction | 1.30 - 7.46 | Manchester Victoria | |
| MVL2 | Stalybridge Junction to Stalybridge Station | 7.46 - 7.74 | Manchester Victoria | |
| MVL3 | Stalybridge Station to Heaton Lodge Junction | 7.74 - 29.45 | Manchester Victoria via Stalybridge | |
| MVL4 | Heaton Lodge South Junction (formerly Heckmondwike Junction) to Heaton Lodge East Junction | 28.78 - 29.74 | Manchester Victoria via Stalybridge | |
| MVL5 | new route | 28.78 - 29.34 | Manchester Victoria via Stalybridge | exact definition unknown |
| MVM | Manchester Victoria and Miles Platting Line | 0.00 - 1.30 | Manchester Victoria | |
| MVN | Manchester Victoria and Normanton Line | see separate portions | ||
| MVN1 | Manchester Victoria to Thorpes Bridge Junction | 0.09 - 2.31 | Manchester Victoria | |
| MVN2 | Thorpes Bridge Junction to Normanton | 2.17 - 50.31 | Manchester Victoria via Rochdale | |
| MVR | Manifold Valley Light Railway | 0.00 - 8.15 | Waterhouses | |
| MVY | Moss Valley Branch | 0.70 - 2.62 | Croes Newydd North Fork Junction | |
| MVZ | Merthyr Vale Branch | 0.00 - 0.24 | Merthyr Vale Junction | |
| MWA | Milton West Junction to Asfordby Junction Line | ?? - ?? | ||
| MWB | Marlow Branch | 0.00 - 2.61 | Bourne End | |
| MWC | Mouldsworth and Helsby West Cheshire Junction Branch | 31.05 - 34.77 | Manchester Central | |
| MWD | Market Weighton and Driffield Line | 0.00 - 13.15 | Market Weighton East Junction | |
| MWF | Mossend West Fork | 0.00 - 0.39 | Mossend West Junction | |
| MWJ | Marcheys House Junction to Winning Crossing Junction Curve | 0.00 - 0.31 | Marcheys House Junction | |
| MWL | March West Line | 0.00 - 0.13 | March West Junction | |
| MWM | Middlesbrough West Marsh Line | 0.00 - 0.36 | junction with MMH1 | |
| MWN | Grimsby Dock Branch | 107.69 - 110.10 | Manchester London Road via Woodhead | |
| MWT | Margam West Curve | 0.00 - 0.33 | Copper Works Junction | |
| MWY | Mwyndy Branch/Brofiscin Branch | 0.00 - 2.63 | Mwyndy Junction | Formerly 0.47 - 3.30 ex Llantrisant Junction |
| MWZ | Monds Works Loop | 0.00 - 0.13 | Mond Works Junction | |
| MYB | Merrybent Branch | 0.00 - 5.68 | Merybent Junction | |
| MYC | Midland Yard Junction to Canal Farm Junction (Nuneaton North Chord) | 0.00 - 0.69 | Midland Yard Junction | |
| MYD | Millerhill Junction to Millerhill Yard Junction Line | 0.00 - 0.71 | Millerhill Junction | = MHE?? |
| MYL | Margam Yard Line | 197.41 - 199.31 | Paddington via Stroud | |
| MYO | Mossend Down Yard | Now ZZD1 | ||
| MYP | Mossend Up Yard | Now ZZC9 | ||
| MYS | Meadows Yard to Seafield Line | ?? - ?? | Edinburgh area | |
| MYT | Maryport Elizabeth Dock Line | 0.00 - 0.56 | Maryport Junction | |
| MYW | Ministry of Works (Westerleigh East) Loop | 106.43 - 107.04 | Paddington | Formerly WLE |