A theatre, film, and TV veteran who rose to fame prominently in the 1960's, after starring in several films including The Iron Maiden and Modesty Blaise. He also starred in TV shows such as Doctor Who and The Emigrants.
In 1950, he worked as an assistant stage manager at Castle Theatre in Farnham, England.
He released his autobiography, The Smallest Giant: An Actor's Tale, in 2005.
He is the son of Donald Gregson, a captain in the 3rd Indian Cavalry, and was born in Poona, British India, what is now Maharashtra, India. He has two sons and one daughter.
He is the uncle to actress Natasha Gregson Wagner.