Several of the characters in the books have visited the Other Railway or used it to travel from place to place. Many of the Fat Controller's engines came from the Other Railway originally. There have been several visitors from the Other Railway.
Although the fictional North Western Railway or Fat Controller's Railway was part of the nationalised railway network it kept most of its operating independence from British Railways on the mainland. This is why it escaped the infamous Beeching Report in the 1960s.
BR ran an hourly suburban train service from Barrow to Ballahoo and Norramby on Sodor.
The Big City Engine, Gordon and Duck were involved in an argument over the confusion between the mainline stations in London. Gordon the Big Engine boasted about going to London, and believed that London was restricted to Kings Cross (served by the London and North Eastern Railway). Duck the Great Western Engine thought that London was Paddington, as he had once worked there as a station pilot (Great Western Railway). The Big City Engine thought that London was Euston (London Midland and Scottish Railway). Unbeknownst to them, they were all correct, but they did not realize, due to being on their own isolated lines before coming to Sodor, that there were a number of stations in London, and that these were merely three of them. Gordon was disappointed to discover when he visited London that the station he visited was St. Pancras.