Born Ronald Moodnick in London, he has worked in a variety of genres, but is perhaps best known for his starring role as the villainous Fagin in the musical Oliver. He created the role in the original West End production, and reprised it on Broadway and in the 1968 film version, for which he was nominated for the Academy Award for Best Actor.
In 1969, he was offered, but declined, the lead role in Doctor Who, following the departure of Patrick Troughton from the role.