He came from a deeply political family with his father, Morrison Barclay, being a Liberal Party member and his uncle John was a Reform Party member. Barclay's other uncle Jim Barclay represented the electorate for the Labour Party from until his defeat in 1943. His cousin Bruce Barclay represented Christchurch Central for the Labour Party from until his death in 1979. He himself joined the Labour Party and in 1933 he was a campaign committee member for Dan Sullivan's mayoral campaign in Christchurch. Likewise in he was a campaign committee member for Tim Armstrong in .