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

Contents

2.1 Joint Railways
2.2 Railways not included in Group Companies

2.2.1 Electric or electric and steam lines
2.2.2 Light and similar railways (standard gauge)
2.2.3 Light railways (other than standard gauge)
2.2.4 Miscellaneous railways

3 See also

The Big Four

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

Great Western Railway (GWR)
- Great Western Railway 3005 miles
- Alexandra (Newport & S Wales) Docks & Railway (ADR) 10.5 miles
- Barry Railway (Barry) 68 miles
- Cambrian Railways (Cambrian) 295.25 miles
- Cardiff Railways (Cardiff) 11.75 miles
- Rhymney Railway (RhyR) 51 miles
- Taff Vale Railway (TVR) 124.5 miles
  - 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
- Great Eastern Railway (GER) 1191.25 miles
- Great Northern Railway (GNR) 1051.25 miles
- Hull and Barnsley Railway 106.5 miles
- North Eastern Railway 1757.75 miles
- Great North of Scotland Railway 334.5 miles
- North British Railway 1378 miles
  - for the list of subsidiary companies and joint railways see
London, Midland and Scottish Railway (LMSR)
- London and North Western Railway (LNWR); 2667.5 miles (4268km)
  - including Lancashire and Yorkshire Railway (L&YR) amalgamated from 1 January 1922
- Furness Railway(Furness); 158 miles (253km)
- Midland Railway (MR) 2170.75 miles (3473km
- North Staffordshire Railway(NSR) 220.75 miles (253km)
- Caledonian Railway (CalR) 1114.5 miles (1783km)
- Glasgow and South Western Railway (GSWR) 493.5 miles (790km)
- Highland Railway(HR) 506 miles (807km)
  - 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 LMSR were:
    - Dundalk, Newry and Greenore Railway (DNGR) 26.5 miles
    - Northern Counties Committee lines (NCC(I)) 265.25 miles
    - Joint Midland and Great Northern Railway of Ireland lines (JtMGNR(I))
Southern Railway (SR)
- London, Brighton and South Coast Railway (LBSCR) 457.25 miles
- London and South Western Railway (LSWR) 1020.5 miles
- 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
  - 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:
- East London Railway : Great Eastern Railway, London, Brighton and South Coast Railway, Metropolitan((Met) and Metropolitan District Railway. Length 5 miles (8km). Managed and operated by Met; goods traffic by LNER.
- Cheshire Lines Committee: (GNR, Midland and GCR); now operated under direction of a board of directors appointed by LNER and LMSR. Length 142 miles (227km) Rolling stock owned by CLC; locomotive power by LNER.
- Manchester, South Junction and Altrincham Railway :
- Midland and Great Northern Joint Railway: (Midland and GNR) Length 183 miles (293km)
- Somerset and Dorset Joint Railway: (Midland and LSWR) Length 105 miles (168km)

Railways not included in Group Companies

Electric or electric and steam lines

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

Light and similar railways (standard gauge)

Bideford, Westward Ho! and Appledore Railway 9.97 miles (16km) closed at time of Grouping
Bishops Castle Railway 9.75 miles (16km)
Corringham Light Railway 2.75 miles (4km)
Derwent Valley Railway 16 miles (26km)
Easingwold Railway 2.5 miles (4km)
East Kent Railway: 48 miles (77km)
Glasgow (Cable) Subway : 6.75 miles (11km)
Hundred of Manhood and Selsey Tramways 8 miles (13km) *
Jersey Eastern Railway 6.25 miles (10km)
Kent & East Sussex Railway: 24 miles (38km) *
Mumbles Railway : 5.5 miles (9km)
Nidd Valley Light Railway : 6 miles (10km) public; 7 miles (11km) private
North Sunderland Light Railway : 4 miles (6km)
Rowrah and Kelton Fell Railway : 3 miles (5km)
Shropshire and Montgomeryshire Railway 26 miles (42km) *
Stocksbridge Railway 2 miles (3km)
Swansea Improvements and Tramways Company 18 miles (29 km)
Wantage Tramway
Weston, Clevedon and Portishead Railway 14.5 miles (23km)

Light railways (other than standard gauge)

Ashover Light Railway
Brighton Electric Railway ; 2 feet 8.5 inches (825mm); 1.75 miles (3km)
[[Camborne and Redruth Tramway; 3 feet 6 inches (1065mm); 3.25 miles (5km)
[[Campbeltown and Machrihanish Railway; 2 feet 3 inches (685mm); 6 miles (10km)
Corris Railway ; 2 feet 3 inches (685mm); 11 miles (18km)
Eskdale Railway ; 15 inch (380mm); 7.25 miles (12km)
Festiniog Railway; 1 foot 11.5 inches (597mm); 14.5 miles (23km)
Glyn Valley Railway ; 2 feet 4.5 inches (725mm)
Isle of Man Railway; 3 feet (762mm); 46.25 miles (74km)
Jersey Railway and Tramways ; 3.5 feet (890mm); 7.5 miles (12km)
Manx Electric Railway; 3 feet (762mm); 18 miles (29km); and 3.5 feet (890mm); 5 miles (8km)
North Wales Narrow Gauge Railway; 1 foot 11.5 inches (597mm); 12.25 miles (20km)
Portmadoc, Beddgelert and South Snowdon Railway ; 1 foot 11.5 inches (597mm); 4.75 miles (8km)
Rye and Camber Tramway ; 3 feet (762mm); 3 miles (5km)
Snailbeach District Railway : 2 feet 4 inches (572mm); 3.25 miles (5km)
Snowdon Mountain Tramroad; 2 feet 7.5 inches (800mm); 5 miles (8km); rack railway
Southwold Railway ; 3feet (762mm); 9 miles (14km)
Tal-l-llyn Railway ; 2 feet 3 inches (685mm); 6.75 miles (11km)
Wolverton and Stony Stratford Railway ; 3 feet 6inches (1065mm); owned by LMSR

Miscellaneous railways

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

Felixtowe Docks and Railway length of railway 0.5 mile (0.8km)
Manchester Ship Canal 156 miles (250km)
Mersey Docks and Harbour Board 104 miles (166km)
Milford Haven Dock and Railway 1.25 miles (2km)
Pentewan Railway, Port and Trading Company 2.5 feet gauge (635mm); 4 miles (6km); temporarily closed 1923
Trafford Park : 18 miles (29km)

List of railway companies involved in the 1923 grouping