Hogan’s Heroe’s.

[Inspector Knacker]

Anyone remember the series set in the P.O.W. camp and the character Sergeant Schultz? He had a catchphrase I KNOW NOTHING! and also I SEE NOTHING, I HEAR NOTHING! in an emphatically gruff German accent.
A man with an erasable memory,  to suit the occasion, when he wanted to avoid trouble.
The Doctor, appearing on Victoria Derbyshire reminded me, accent apart, of Sergeant Schultz almost immediately.