Sir Ken McCallum says he is a fan of the show that has been described as the anti-James Bond.
The director general of MI5 has described himself as a "Slow Horses man", saying he is a fan of the spy thriller TV series.
The Apple TV+ show, described by some critics as the anti-James Bond, stars Sir Gary Oldman as the crude boss of a team of failed or disgraced MI5 agents who have been banished to a building called Slough House.
In a video post on MI5's official Instagram account, Sir Ken McCallum was asked "what do you really think about your friends over the river at MI6?"
"You might want to say there is room for both James Bond and Slow Horses," he said, adding "I happen myself to be a Slow Horses man".
He said: "I suppose maybe the person who wrote the question wanted to hear that there's some rivalry or whatever – the truth is they are our friends, they are our colleagues."
