An attempt to tabulate which 1923 groupings and BR regions the original companies were absorbed by.

NOTE:

Work in progress.

exclam:

Alexandra (Newport and South Wales) Docks
Axholme Joint
Ashby and Nuneaton Joint
Bere Alston and Cadstock
Bishop's Castle
Birkenhead Joint
Brackenhill
Brecon and Merthyr
Burry Port and Gwendraeth Valley
Barry
Bideford, Westward Ho! and Appledore
Caledonian
Cambrian
Cardiff
Clifton Extension
Citadel Station Joint
Cockermouth, Keswick and Penrith
Cheshire Lines
Campbeltown and Machrihanish
Cleobury Mortimer and Ditton Priors
Croydon and Oxted Joint
Colne Valley and Halstead
Cleator and Workington Junction
Dundee and Arbroath Joint
Dumbarton and Balloch Joint
Dentonholme Joint
Dearne Valley
Derwent Valley

 exclam:

 LMS -> BR(Scot)
 
 LMS -> BR(Mid)
 
LNER -> BR(Scot)

LNER -> BR(North)

LNER -> BR(East)

SR -> BR(South)

GWR -> BR(West)

Joint

 Independent

Looks like you've got a life's work there.  :)

The Railway Magazine managed to do this many years ago.  I wonder if you might get a quicker completion by searching their digital archive

Hi

I have a copy of C J Wignall's British Railways Maps and Gazeteer covering 1830-1981.  Oxford Press.  It includes lists of mainland stations and companies plus separate lists for Ireland.

There are a few on eBay for about £20-25.

This is my go-to book for lines and stations in whatever areas I am researching.

Might save a fair bit of time.

I am happy to attempt a scan of the 6 pages of companies of required.

Barry