I stumbled upon this at IMDb.com:

Not to be confused with the 1967 TV series of the same name (also
starring Patrick McGoohan), this adaptation of Bridget Boland's 1954
stage play depicts the conflict between a Cardinal (allegedly inspired
by real-life Hungarian Cardinal Mindszenty) in an unnamed totalitarian
state and the Interrogator who tries to force him into a public abjure
of his religious convictions.

Alan Badel as The Cardinal

Patrick McGoohan as The Interrogator

Written by Bridget Boland



Perhaps "Who is Number 1?" is also a sly humorous reference to
this? ;-)