Cary was born in Kildare, Ireland, and educated at Aldenham School and Trinity College, Dublin.
[1] He trained as a doctor, and established a successful practice, first in Yorkshire and then in London.
During his student days he developed a lifelong love of the theatre, and in 1946 he gave up his medical practice to concentrate on writing plays.
[2] In addition to his comedies, Cary wrote stage thrillers, and original works and adaptations for television and cinema.
[3] His plays were popular with amateur drama groups, and he made a substantial income in royalties from that quarter.