List of railway companies involved in the 1923 grouping

Under the Railways Act 1921 the majority of the railway companies in Great Britain (along with a few in Northern Ireland) were grouped into four main companies, often termed the Big Four. The grouping took effect from 1 January 1923.

The Big Four

The Big Four and their constituent companies, showing route mileage, were:

Great Western Railway (GWR)
- Great Western Railway 3,005 miles (4,836 km)
- Alexandra (Newport & S Wales) Docks & Railway (ADR) 10.5 miles (16.9 km)
- Barry Railway (Barry) 68 miles (109 km)
- Cambrian Railways (Cambrian) 295.25 miles (475.16 km)
- Cardiff Railway (Cardiff) 11.75 miles (18.91 km)
- Rhymney Railway (RhyR) 51 miles (82 km)
- Taff Vale Railway (TVR) 124.5 miles (200.4 km)
  - for the list of subsidiary companies and joint railways see List of constituents of the Great Western Railway
London and North Eastern Railway (LNER)
- Great Central Railway (GCR) 852.5 miles (1,372.0 km)
- Great Eastern Railway (GER) 1,191.25 miles (1,917.13 km)
- Great Northern Railway (GNR) 1,051.25 miles (1,691.82 km)
- Hull and Barnsley Railway (H&BR) 106.5 miles (171.4 km)
- North Eastern Railway (NER) 1,757.75 miles (2,828.82 km)
- Great North of Scotland Railway (GNSR) 334.5 miles (538.3 km)
- North British Railway (NBR) 1,378 miles (2,218 km)
  - for the list of subsidiary companies and joint railways see List of constituents of the London and North Eastern Railway
London, Midland and Scottish Railway (LMS)
- London and North Western Railway (LNWR); 2667.5 miles (4268 km)
  - including Lancashire and Yorkshire Railway (L&YR) amalgamated from 1 January 1922
- Furness Railway (Furness); 158 miles (253 km)
- Midland Railway (MR) 2170.75 miles (3473 km)
- North Staffordshire Railway (NSR) 220.75 miles (253 km)
- Caledonian Railway (CalR) 1114.5 miles (1783 km)
- Glasgow and South Western Railway (GSWR) 493.5 miles (790 km)
- Highland Railway (HR) 506 miles (807 km)
  - for the list of subsidiary companies and joint railways see List of constituents of the London, Midland and Scottish Railway
- Irish Lines absorbed by the LMS were:
  - Dundalk, Newry and Greenore Railway (DNGR) 26.5 miles (42.6 km)
  - Northern Counties Committee lines (NCC(I)) 265.25 miles (426.88 km)
  - Joint Midland and Great Northern Railway (Ireland) lines (JtMGNR(I))
Southern Railway (SR)
- London, Brighton and South Coast Railway (LBSCR) 457.25 miles (735.87 km)
- London and South Western Railway (LSWR) 1,020.5 miles (1,642.3 km)
- South Eastern and Chatham Railways' Managing Committee: a working union of the South Eastern Railway and the London, Chatham and Dover Railway 637.75 miles (1,026.36 km)
  - for the list of subsidiary companies and joint railways see List of constituent companies of the Southern Railway

Companies not covered by the Grouping

Over fifty railway companies were not covered by the Grouping. Those in the following list were those organised on an independent basis, usually providing locomotives and rolling stock also. They are included under classification headings.

Joint Railways

Joint Lines in this respect were wholly owned by two or more other companies. If not all of the owning companies went into the same group then the joint company could not be grouped. Joint lines did not always operate any services: they owned the track, stations etc. and the services were operated by one or more of the parent companies:

These are those in which the Group companies only are concerned:
- Cheshire Lines Committee: (GNR, Midland and GCR); now operated under direction of a board of directors appointed by LNER (2/3) and LMS (1/3). Length 142 miles (227 km) Rolling stock owned by CLC; locomotive power by LNER.
- Great Western and Great Central Joint Railway: GWR and GCR; subsequent to the Grouping the parent companies were the GWR and the LNER, but the title was not altered.
- Manchester, South Junction and Altrincham Railway: LNWR and GCR; subsequent to the Grouping the parent companies were the LMS and the LNER.
- Midland and Great Northern Joint Railway: (Midland and GNR; subsequent to the Grouping the parent companies were the LMS and the LNER). Length 183 miles (293 km). This was the largest joint system in the UK, and many of the services were operated by the joint company itself. In addition, it received substantial traffic from the GNR and MR/LMS, but rather less post-Grouping from the LNER (which also owned the competing ex-GER system in East Anglia).
- Somerset and Dorset Joint Railway: (Midland and LSWR) Length 105 miles (168 km)
Joint lines where one or more partners were ungrouped:
- Aylesbury Station: joint between the GW & GC Joint and the Metropolitan and Great Central Joint Committee
- East London Railway: prior to Grouping, this railway was owned one-sixth each by the Great Eastern Railway, London, Brighton and South Coast Railway, Metropolitan Railway, District Railway; and one-third by the South Eastern and Chatham Railway (as successors to the London, Chatham and Dover Railway and South Eastern Railway, who had owned one-sixth each). After Grouping, it was owned half by the Southern, and one-sixth each by the LNER, Metropolitan and District. Length 5 miles (8 km). Managed and operated by Met; goods traffic by LNER.
- Metropolitan and Great Central Joint Committee: prior to Grouping, owned by the Metropolitan Railway and GCR; post-Grouping, Metropolitan and LNER.

Railways not included in Group Companies

Electric or electric and steam lines

Railways associated with the Underground Electric Railways Company of London (the precursor of the London Passenger Transport Board (LPTB)):
- Central London Railway: 7 miles (11 km). Trains worked through to Ealing over the Ealing and Shepherd's Bush Railway (GWR)
- City and South London Railway: 7.25 miles (12 km)
- London Electric Railway: 24 miles (38 km): amalgamation of the Baker Street and Waterloo Railway, Great Northern, Piccadilly and Brompton Railway and Charing Cross, Euston and Hampstead Railway
- District Railway 27.75 miles (44 km)
Other electric/steam railways:
- Liverpool Overhead Railway: 6.5 miles (10 km)
- Mersey Railway: 4.75 miles (8 km)
- Metropolitan Railway: steam and electric 65.75 miles (105 km) including the Great Northern and City Railway

Light and similar railways (standard gauge)

Bideford, Westward Ho! and Appledore Railway 7 miles (11 km) closed at time of Grouping
Bishops Castle Railway 9.75 miles (16 km)
Corringham Light Railway 2.75 miles (4 km)
Derwent Valley Light Railway 16 miles (26 km)
Easingwold Railway 2.5 miles (4 km)
East Kent Railway: 48 miles (77 km)
Glasgow (Cable) Subway: 6.75 miles (11 km)
Hellingly Hospital Railway: 1.25 miles (2 km)
Hundred of Manhood and Selsey Tramways 8 miles (13 km) *
Kent & East Sussex Railway: 24 miles (38 km) *
Mumbles Railway: 5.5 miles (9 km)
Nidd Valley Light Railway: 6 miles (10 km) public; 7 miles (11 km) private
North Sunderland Light Railway: 4 miles (6 km)
Rowrah and Kelton Fell Railway: 3 miles (5 km)
Shropshire and Montgomeryshire Railway 26 miles (42 km) *
Stocksbridge Railway 2 miles (3 km)
Swansea Improvements and Tramways Company 18 miles (29 km)
Wantage Tramway 2 miles (3 km)
Weston, Clevedon and Portishead Railway 14.5 miles (23 km)

Light railways (narrow gauge)

Ashover Light Railway 2 ft (610 mm); 7.25 miles (12 km)
Brighton Electric Railway; 2 feet 8.5 inches (825 mm); 1.75 miles (3 km)
Camborne and Redruth Tramway; 3 ft 6 in (1,067 mm); 3.25 miles (5 km)
Campbeltown and Machrihanish Railway; 2 ft 3 in (686 mm); 6 miles (10 km)
Corris Railway; 2 ft 3 in (686 mm); 11 miles (18 km)
Ravenglass and Eskdale Railway; 15 in (381 mm); 7.25 miles (12 km)
Ffestiniog Railway; 1 ft 11 ¹⁄₂ in (597 mm); 14.5 miles (23 km)
Glyn Valley Railway; 2 feet 4.5 inches (725 mm); 8.25 miles (13 km)
North Wales Narrow Gauge Railways; 1 ft 11 ¹⁄₂ in (597 mm); 12.25 miles (20 km)
Portmadoc, Beddgelert and South Snowdon Railway; 1 ft 11 ¹⁄₂ in (597 mm); 4.75 miles (8 km)
Rye and Camber Tramway; 3 ft (914 mm); 3 miles (5 km)
Snailbeach District Railways: 2 feet 4 inches (572 mm); 3.25 miles (5 km)
Snowdon Mountain Tramroad; 800 mm (2 ft 7 ¹⁄₂ in); 5 miles (8 km); rack railway
Southwold Railway; 3 ft (914 mm); 9 miles (14 km)
Talyllyn Railway; 2 ft 3 in (686 mm); 6.75 miles (11 km)
Wolverton and Stony Stratford Tramway; 3 ft 6 in (1,067 mm); owned by LMSR

Railways outside the jurisdiction of the United Kingdom Parliament

Alderney Railway
Guernsey Railway
Isle of Man Railway; 3 ft (914 mm); 46.25 miles (74 km)
Jersey Eastern Railway 6.25 miles (10 km)
Jersey Railway and Tramways; 3 ft 6 in (1,067 mm); 7.5 miles (12 km)
Manx Electric Railway; 3 ft (914 mm); 18 miles (29 km); and 3 ft 6 in (1,067 mm); 5 miles (8 km)

Miscellaneous railways

The railways included in this section were standard gauge, unless otherwise noted:

Felixstowe Docks and Railway length of railway 0.5 mile (0.8 km)
Manchester Ship Canal 156 miles (250 km)
Mersey Docks and Harbour Board 104 miles (166 km)
Milford Haven Dock and Railway 1.25 miles (2 km)
Pentewan Railway 2 ft 6 in (762 mm); 4 miles (6 km); temporarily closed 1923
Trafford Park: 18 miles (29 km)