The RCA became the Transport Salaried Staffs' Association (TSSA), and Collings was elected to its executive committee in 1945, serving until 1951. On the executive, he argued in favour of equal pay and opportunities for women and black workers. He represented the union on the London Trades Council, and from 1948 to 1949, he served as the trades council's chair. He also represented the union on the executive of the National Federation of Professional Workers. From 1946, he was a member of the Labour Research Department's executive, serving as vice-chair in 1948/49.[2][3]