A list I compiled, with help from others, a while back
Ex BR lines - north to south
High Street (Glasgow) - Bridgeton Central
Balloch - Balloch Pier
Shildon - Newport (freight only) **
Newcastle Quayside branch (freight only) **
Riverside branch, Byker - Percy Main via Walker **
Carlisle avoiding line (freight)
Lancaster Castle - Green Ayre - Morecambe Promenade
Southport - Crossens
Bury - Holcombe Brook **
A short section of the Bolton branch at Radcliffe Central electrified for short workings
Altrincham station half way to Hale (for reversing EMUs)
Altrincham station to carriage depot (former Bowdon station)
Bootle – Aintree via Ford (North Mersey branch) **
Edge Hill Gridiron and circular railway
Woodhead line (Hadfield - Sheffield Vic - Rotherwood/Wath) and branches
Watford High Street - Croxley Green
Watford High Street - Rickmansworth (ex-LNWR)
South Acton - Kew Curve East Jn - Kew Bridge (still in use for freight, de-electrified)
Camden Road - Primrose Hill - South Hampstead (still open for freight, ecs and diversions)
Graham Road Curve (Hackney)
Tilbury Riverside branch
Nunhead - Crystal Palace HL
Elmer's End - Addiscombe
Woodside - South Croydon
Dover Marine/Western Docks branch
Folkestone Harbour branch
Horsted Keynes - Haywards Heath (part still in use for stone traffic)
** de-electrified before closure
London Underground lines
Epping - Ongar
Acton Town - South Acton
Farringdon - Moorgate "widened lines"
Holborn - Aldwych, Piccadilly Line ) although closed to passengers, these lines are still
Green Park - Charing Cross, Jubilee Line) operational and electrified
Other obscure spurs and connections, especially in the London area, also disused stations and their
approaches such as Liverpool Exchange, Holborn Viaduct, Broad Street and Coulsdon North.
Industrial lines
Harton Electric Railway (South Shields)
Kearsley Power Station
Light railways
Swansea & Mumbles Railway
Grimsby & Immingham Electric Railway #
Burton & Ashby Light Railway #
Kinver Light Railway #
Llandudno & Colwyn Bay Electric Railway #
Liverpool Overhead Railway
Also lines now forming part of Tyne & Wear Metro, Manchester Metrolink and Croydon Tramlink.
Urban street tramways are excluded (the above marked # had some street running)