The by-election was held due to the death of the incumbent Labour MP, Alfred Onions.

[1] Morgan Jones clinched the Labour nomination despite not being the preferred candidate of the South Wales Miners' Federation.

He was the first conscientious objector to be elected to Parliament after World War I.

[2] The Communist Party of Great Britain (CPGB) stood Bob Stewart, a member of its executive committee.

[3] Jones won an easy victory, with Edmunds in second, and the CPGB a distant third.