In 1945, Wegg-Prosser was elected to Paddington Metropolitan Borough Council, soon becoming chair of its finance committee, and then leader of the Labour group on the council. He stood unsuccessfully in Paddington South at the 1945, 1950, 1951 and 1955 UK general elections. He campaigned against Peter Rachman, was the first chair of the North Kensington Law Centre, and was the first Labour activist to be elected to the governing body of the Law Society.
