[1] O'Casey was born in Montreal, Quebec, to poet father, Michael Casey, and actress mother, Margaret Sheehy, a Dubliner who had co-starred with the young James Joyce in his first stage role.
O'Casey was at one time a leading ice hockey player in his native Montreal, skills which he was able to put to use during the filming of children's adventure serial The New Forest Rustlers, in which he played the leader of a gang planning to steal a priceless Rembrandt.
[3][4] O'Casey's comedy talents brought him his best known role, as Jeff Rogers, Canadian son-in-law of Peggy Mount, in the TV sitcom The Larkins (1958–64).
He was host of ITV's charades gameshow Don't Say a Word (1963),[5] a panel game with two teams led by Libby Morris and Kenneth Connor.
[9] As literary head of the production company Commonwealth United, O'Casey was an associate producer on Terry Southern's The Magic Christian (1969) with Ringo Starr, Peter Sellers and a soundtrack by Badfinger.