Mr Johnstone is a fictional character portrayed by Nicholas Selby in the TV series Agatha Christie's Poirot.
In the first episode they appeared in, titled The Double Clue (season 3), they were 65 years old.
They appear in 1 episodes out of a total of 70 aired
Episodes1
The Double Clue
episode S3.E7 february 1991Poirot helps Chief Inspector Japp try to find a jewel thief, but is sidetracked when a bewitching Russian countess arrives on the scene.