From Wikipedia

Chesney Allen, born William Ernest Chesney Allen (5 April 1893 – 13 November 1982) was a popular English entertainer of the Second World War period. He is best remembered for his double act with Bud Flanagan, Flanagan and Allen

He began his career in straight acting, making his debut in stock at the Wimbledon Theatre, London, in 1912. Serving in Flanders in the First World War, he made friends with Bud Flanagan, and worked with him from 1924. As music hall comedians, they would often feature a mixture of comedy and music in their act and this led to a successful recording career and roles in film and television. Flanagan and Allen were also members of the Crazy Gang and worked together in that team for many years.

Flanagan and Allen stopped performing together with Chesney Allen's retirement on health grounds.