The Southern Railway was one of the "Big Four" railway companies set up after the 1923 Grouping. This list sets out the constituents of the Company.

Constituent companies

• The London and South Western Railway (LSWR) route mileage 1020 miles (1632km)
• The London, Brighton and South Coast Railway (LBSCR) 457.25 miles (736km)
• The combined systems of the South Eastern Railway and the London, Chatham and Dover Railway, under the South Eastern & Chatham Railways' Managing Committee (SECR) 637.75 miles (1026km). These concerns had amalgamated under a Managing Committee on 1 January 1922.

Subsidiary companies

Independently operated lines

• Freshwater, Yarmouth and Newport (Isle of Wight) Railway 12 miles (19km)
• Isle of Wight Railway 15.25 miles (24km)
• Isle of Wight Central Railway 28.5 miles (46km)
• Bere Alston and Callington section of the Plymouth, Devonport and South Western Junction Railway 9.75 miles (16km)

Non-working companies

• Originally leased to or worked by LSWR
  • Bridgewater Railway 7.25 miles (12km)
  • Lee-on-the-Solent Railway 3 miles (5km)
  • North Cornwall Railway 52.5 miles (84km)
  • Plymouth and Dartmoor Railway (portion used by LSWR) 2.25 miles (4km)
  • Plymouth, Devonport and South Western Junction Railway (except Bere Alston and Callington section as above) 19.5 miles (31km)
  • Sidmouth Railway 8.25 miles (13km)
• Originally leased to or worked by LBSCR
  • Brighton and Dyke Railway 4.75 miles (8km)
  • Hayling Railway 5 miles (8km)

Originally leased to or worked by SER or LCDR

• London and Greenwich Railway 3.75 miles (6km)
• Mid Kent Railway (Bromley to St Mary Cray) 2.5 miles (4km)

Other railways

• Victoria Station and Pimlico Railway (in which the Great Western Railway and the London and South Western Railway were also parties)
• Lynton and Barnstaple Railway: not covered by the Railways Act 1921, but absorbed by the LSWR. 19.25 miles (31km)

Joint companies

• In 1923, now comprised wholly in the SR:
  • Croydon & Oxted Railway 12.5 miles (20km (was SE&CR))
  • Dover & Deal Railway 8.5 miles (14km) (was SE&CR)
  • Epsom & Leatherhead Railway 3.75 miles (6km) (was LBSCR/LSWR joint)
  • Portsmouth & Ryde Railway (the ferry) 8.5 miles (14km) (was LBSCR/LSWR joint)
  • Tooting, Merton & Wimbledon Railway 5.75 miles (9km) (was SE&CR)
  • Woodside & South Croydon Railway 2.5 miles (4km) (was LBSCR/ SE&CR joint)
• In 1923, in association with other companies:
  • East London Railway 5 miles (8km) (1/3 share with London and North Eastern Railway and Metropolitan Railway)
  • Easton & Church Hope Railway 3.5 miles (6km) (jointly with Great Western Railway (GWR))
  • Somerset and Dorset Joint Railway 105 miles (168km) (with London, Midland and Scottish Railway (LMSR))
  • West London Extension Railway 5.25 miles (8km) (shares with GWR and LMSR)
  • Weymouth & Portland Railway 5.5 miles (9km) (jointly with GWR)

The information in this article taken from the Railway Magazine for February 1923

See also