The London, Midland and Scottish Railway (LMS) was created under the terms of the Railways Act 1921. The first schedule to that Act listed four groups, and for each, a number of "Constituent Companies" were listed, as were a number of subsidiary companies. The constituent companies would amalgamate to create a new railway company, and the subsidiary companies would be absorbed either by one of the constituent companies prior to the amalgamation, or by the new railway company after amalgamation. The group that was to become the LMS was described in the Act as "the North Western, Midland and West Scottish Group".