[3] He is probably best known for his role as radio boss Don Satchley in the BBC television detective series Shoestring, as well as for playing Scrooge's nephew Harry in the film version of Scrooge, a musical based on Charles Dickens' A Christmas Carol, and for his role in The Army Game, a British television comedy series of the late 1950s and early 1960s.

With Bernard Bresslaw, Leslie Fyson and Alfie Bass, he took the theme tune from The Army Game into the UK Singles Chart in 1958, where it peaked at number 5.

[2] In 1961, Medwin played the lead named Michael in BBC Radio Light Programme comedy series about an advertising company called Something to Shout About.

He also said that Charles Laughton and Edward G. Robinson were the two biggest influences in his life of acting, and considered that being appointed OBE (Officer of the Order of the British Empire) in the 2005 Queens Birthday Honour's List for Services to Drama the single greatest thing that ever happened to him.

[12] As a play producer, his work includes Spring and Port Wine, Alpha Beta, A Day in the Death of Joe Egg, Forget Me Not Lane and Another Country.