 Lonsdale was born in Paris and brought up by an Irish mother and an English father, initially on the island of Guernsey, then in London in 1935, and later, during World War II, in Casablanca, Morocco.He returned to Paris to study painting in 1947, but was drawn into the world of acting instead, first appearing on stage at the age of 24.Lonsdale is bilingual and has appeared in both English- and French-language productions.