For safety reasons the guard's brake van at the rear of a goods train would come from the same company as the loco at the front. This is not as restricting as it may seem however as it was not uncommon to see one companies train on another companies line. An example of this kind of working is where one company allowed a locomotive and brake van from a second company to access a marshaling yard or set of 'exchange sidings' to collect traffic for destinations on the second line.
When a company had no lines to a particular town it had the option of applying to Parliament for 'running powers' over another companies lines. The London & North Western Railway reached the City of London and the docks via the North London Railway and lines owned by the Great Western. In Scotland the Midland Railway gained access to Edinburgh and Glasgow via lines owned by the North British Railway and Glasgow & South Western Railways. These arrangements were sometimes amicable but in some cases relations became strained.
Another option was to join with another company to build a new line or buy up an existing company. There were a lot of jointly owned or jointly operated lines dotted round the country. At the lower end of the scale the North Staffordshire Railway was joint owner with the Great Central of the short Macclesfield Bollington & Marple Railway. The Great Northern Railway and the Midland Sheffield and Lincolnshire Railway (forerunner to the Great Central Railway) jointly purchased the West Riding & Grimsby line. At the other end of the scale the GCR and GNR and teamed with the Midland to buy up four companies in the North West and establish the Cheshire Lines Committee, one of the biggest joint lines in the country.
The last major route built by the GCR was a second approach to London via Princes Riseborough and High Wycombe, constructed jointly with the GWR and opened to passengers in 1906. The GNR and LNWR had a number of joint lines in Nottinghamshire and Leicestershire. The LNWR held joint ownership with the Lancashire & Yorkshire Railway of the North Union and Preston & Wyre Railways, including joint ownership of the docks at Preston and Fleetwood and the LNWR also held joint ownership with the GWR of the line northwards from Chester to Birkenhead. The coal carrying Severn & Wye Railway in the Forest of Dean was jointly operated by the Midland Railway and the GWR. The Great Eastern and Great Northern railways built a joint spur from near Doncaster into the heart of the Yorkshire coal fields.
In Scotland the Caledonian Railway and Glasgow & South Western Railway shared Bridge Street terminus in Glasgow and most of the line for Irish traffic from Carslile to Stranraer was jointly operated by the Glasgow & South Western and the Caledonian Railway, along with the London & North Western and the Midland Railways of England.
Not all joint operations included goods traffic, East Coast Joint Stock refers to a pooled fleet of purpose built passenger coaches set up in the 1860's to run through services between London and Edinburgh. ECJS stock was jointly owned by the Great Northern Railway, North Eastern, and North British Railways to The 10 a.m. trains from Edinburgh Waverley and Kings Cross were known as the Flying Scotsman by the 1870's. Similarly West Coast Joint Stock was a pool of passenger coaches to run services between London & Glasgow jointly owned by the Caledonian and the LNWR.
The smaller joint lines had no locomotives or rolling stock in their own livery, everything being provided by the owning companies. A few of the larger joint operations owned some stock, some of which remained in their livery after the 1923 grouping. There were three major joint lines which remained as such after the grouping, in order of route mileage these were; Midland & Great Northern, Cheshire Lines Committee and Somerset & Dorset Joint Railway.