McCarthy had an extensive career in film, television and theatre. McCarthy appeared in films such as Zulu, Where Eagles Dare, Time Bandits and Clash of the Titans. He also made guest appearances on television shows such as Danger Man, The Saint, Dixon of Dock Green, No Hiding Place, The Avengers, Department S, Randall and Hopkirk (Deceased), Jason King, Freewheelers, Z-Cars, Return of the Saint and Emmerdale.