"a recherché treat"

TV Screen Plays: The Theatre Plays on British Television Database has soft launched, a searchable resource collecting information about plays broadcast on television between the last thirties and mid-60s (the full data will be available by the summer). Luke McKernan has a review:

"Nowadays theatre on television is a recherché treat, generally reserved for the occasional outing on BBC Four. In the first three to four decades of British television, theatre was a mainstay of broadcast output. In part this was due to a BBC that believed that theatre was elevating, something to be transmitted to the masses because it was good for them. Television was a looking glass through which to discover the better arts."

Of course I've gone straight in and found appearance from the Doctors.

William Hartnell - Seagulls over Sorrento [excerpt] (1953)

Patrick Troughton - four whole pages worth of productions starting in 1947 with Edward II.

Jon Pertwee - Toad of Toad Hall (1946), The Wandering Jew (1947), Ranch in the Rockies [excerpts] (1952), Dick Whittington and His Cat (1958).

Tom Baker - The Millionairess (1972)

Everyone else is to young. We'll return to this when the full database has been posted.