List of constituents of the Southern Railway

The Southern Railway in the United Kingdom 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 1,020 miles (1,642 km)
 * The London, Brighton and South Coast Railway (LBSCR) $457 1/4$ miles (736 km)
 * The combined systems of the South Eastern Railway and the London, Chatham and Dover Railway, under the South Eastern & Chatham Railways' Managing Committee (SECR) $637 3/4$ miles (1026 km). These concerns had formed a working union to operate their services under a Managing Committee on 1 January 1899.

Independently operated lines

 * Freshwater, Yarmouth and Newport Railway 12 miles (19 km)
 * Isle of Wight Railway $15 1/4$ miles (24 km)
 * Isle of Wight Central Railway $28 1/2$ miles (46 km)
 * Bere Alston and Callington section of the Plymouth, Devonport and South Western Junction Railway $9 3/4$ miles (16 km)

Non-working companies

 * Originally leased to or worked by LSWR
 * Bridgewater Railway $7 1/4$ miles (12 km)
 * Lee-on-the-Solent Railway 3 miles (5 km)
 * North Cornwall Railway $52 1/2$ miles (84 km)
 * Plymouth and Dartmoor Railway (portion used by LSWR) $2 1/4$ miles (4 km)
 * Plymouth, Devonport and South Western Junction Railway (except Bere Alston and Callington section as above) $19 1/2$ miles (31 km)
 * Sidmouth Railway $8 1/4$ miles (13 km)
 * Originally leased to or worked by LBSCR
 * Brighton and Dyke Railway $4 3/4$ miles (8 km)
 * Hayling Railway 5 miles (8 km)
 * Originally leased to or worked by SER or LCDR
 * Cranbrook and Paddock Wood Railway 11 mi
 * Crowhurst, Sidley and Bexhill Railway 4 mi
 * London and Greenwich Railway $3 3/4$ miles (6 km)
 * Mid Kent Railway (Bromley to St Mary Cray) $2 1/2$ miles (4 km)

Other railways

 * Victoria Station and Pimlico Railway (in which the Great Western Railway and the London and North Western Railway were also parties)
 * Lynton and Barnstaple Railway: not covered by the Railways Act 1921, but absorbed by the LSWR. Narrow gauge  $19 1/4$ miles (31 km)
 * Several light railways, including the Basingstoke and Alton Light Railway, though other candidate lines remained independent, such as the Kent and East Sussex Railway

Joint companies

 * In 1923, now comprised wholly in the SR:
 * Croydon & Oxted Joint Railway $12 1/2$ miles (20 km (was LBSCR/SE&CR joint)
 * Dover & Deal Railway $8 1/2$ miles (14 km) (was SE&CR)
 * Epsom and Leatherhead Railway $3 3/4$ miles (6 km) (was LBSCR/LSWR joint)
 * Portsmouth and Ryde Joint Railway (including a ferry) $8 1/2$ miles (14 km) (was LBSCR/LSWR joint)
 * Tooting, Merton and Wimbledon Railway $5 3/4$ miles (9 km) (was LBSCR/LSWR joint)
 * Woodside & South Croydon Railway $2 1/2$ miles (4 km) (was LBSCR/SE&CR joint)
 * In 1923, in association with other companies:
 * East London Railway 5 miles (8 km) (shared with London and North Eastern Railway (LNER) and Metropolitan Railway)
 * Easton & Church Hope Railway $3 1/2$ miles (6 km) (joint with Great Western Railway (GWR))
 * Somerset and Dorset Joint Railway 105 miles (168 km) (joint with London, Midland and Scottish Railway (LMS))
 * West London Extension Railway $5 1/4$ miles (8 km) (shared with GWR and LMS)
 * Weymouth & Portland Railway $5 1/2$ miles (9 km) (joint with GWR)