The Amalgamated Society of Railway Servants of England, Ireland, Scotland and Wales was founded in 1872. In 1892 it absorbed the Amalgamated Society of Railway Servants of Scotland. It was the dominant partner in the 1913 amalgamation with the General Railway Workers' Union and the United Pointsmen's and Signalmen's Society which established the National Union of Railwaymen.
Reference: P.S. Bagwell, The Railwaymen: History of the National Union of Railwaymen (2 vols; George Allen and Unwin, 1963 & 1982).
From the guide to the Papers of the Amalgamated Society of Railway Servants of England, Ireland, Scotland and Wales, 1875-1913, (Modern Records Centre, University of Warwick Library)