Reginald Tate (Leblanc) and André Morell (Albert Schweitzer) are both best known for playing Professor Bernard Quatermass in one of the three BBC "Quatermass" serials from the 1950s: Tate in The Quatermass Experiment (1953) and Morell in Quatermass and the Pit (1958).
The earliest complete surviving example of a British television play.