 By 1921, the union had 115,897 members.Within the union, members of its predecessors were reluctant to merge their branches, with the tram and bus drivers coming into particular conflict.Two branches of the union, dominated by bus drivers, broke away in 1921 to form the Trams, Omnibus and Tube Workers union, but Ernest Bevin persuaded them to rejoin later in the year, shortly before the entire union became part of the new Transport and General Workers' Union.