Which British actor starred in both The Two Faces of Dr. Jekyll and The Larkins?
The Two Faces of Dr. Jekyll:  It was directed by Terence Fisher, and stars Paul Massie as Dr. Jekyll, and co-stars Dawn Addams, Christopher Lee and David Kossoff. David Kossoff:  Perhaps his best-known roles were Alf Larkin in "The Larkins" and Professor Kokintz in "The Mouse that Roared" (1959) and its sequel "The Mouse on the Moon" (1963).
David Kossoff