Sherlock star Mark Gatiss: The King and I

King Charles I is a dream role for Sherlock star Mark Gatiss — except for the long wig and moustache.

“It’s like a crowd of flies around my face and a perfect storm of annoyance,” he said after opening night of 55 Days at the Hampstead Theatre, where Stephen Fry and Zoe Wanamaker were in the audience.

Otherwise the part is tailor-made for the writer-actor, who is fascinated by the period covering Charles’s beheading in 1649, and the ensuing years when England was governed without a monarchy.

“I’ve always wanted to play Charles I because he’s a mass of contradictions and that intrigued me,” he said. Yet Gatiss is no royalist and described Charles I as “slippery”.

“I’m a republican. I’m very proud of our country having the first revolution. Oliver Cromwell wanted to bring in decimalisation in the 1650s — instead it took until 1970. It’s the most remarkable thing, we threw it all away and went back to the monarchy.”

Gatiss, 46, co-creator and writer of Sherlock, as well as playing Holmes’s brother Mylock, will return to the BBC hit after his run as the ill-fated monarch.