The London and North Eastern Railway (LNER) was formed out of a number of constituent railway companies at the grouping in 1923.
Main companies
The main companies, showing their route mileage, were:
- Great Eastern Railway (GER) miles (1,906 km)
- Great Central Railway (GCR) miles (1,364 km)
- Forcett Depot line (County Durham) miles (9 km)
Joint railways
Now totally LNER
- Great Northern and Great Eastern Joint Railway
- Hull and Barnsley and Great Central Joint Railway
Joint with LMS
- Axholme Joint Railway
- Cheshire Lines Committee ( share)
- Caledonian and Dunbartonshire Junction Railway (including Loch Lomond steamers)
- Dundee and Arbroath Railway (including Carmyllie Light Railway)
- Great Central and Midland Joint Railway
- Great Central & North Staffordshire Joint Railway
- Great Northern and London and North Western Joint Railway
- Halifax and Ovenden Junction Railway
- Methley Railway ( share)
- Midland and Great Northern Joint Railway
- Norfolk and Suffolk Joint Railway ( share)
- Oldham, Ashton and Guide Bridge Railway
- Otley & Ilkley Railway
- Perth General Station ( share)
- Prince's Dock, Glasgow ( share)
- South Yorkshire Joint Railway ( share)
- Swinton and Knottingley Joint Railway
- Tottenham & Hampstead Junction Railway
Joint with GWR
- Great Western and Great Central Joint Railway