sentences:  After the war, the LMS began to produce its own, the so-called "porthole" stock with round windows to the lavatory compartment.After nationalisation in 1948, as the main carriage works of the London Midland Region, the first Mk I all-steel carriages were produced.The works became the principal rolling stock works of the London Midland Region of British Railways at nationalisation in 1948; the steel British Railways Mark 1 carriage was developed in the 1950s, and at the beginning of the 1950s the works employed over 5,000 people.