Landen was born at Margate. He made his television debut in 1959 as Pip, in an adaptation of Great Expectations, and made his film debut in 1962. He first became well known when he starred in the TV series, Mickey Dunne, during the 1960s. For a time he was regarded as trendy, but had a distinguished parallel career as a stage actor. He died of mouth cancer at his home in Fakenham, Norfolk.