Shot back-to-back with its sequel, Dead Reckoning Part Two, Gatiss said it is an "extraordinary experience" in an exclusive interview.
"It’s absolutely enormous. It’s like Bond – in fact, it’s bigger than Bond!" he told RadioTimes.com at the opening night of new theatre production Horse-Play. "The scale is unbelievable. What’s rather reassuring and lovely is that everyone in it is so charming, fun and nice to be around."
But the Sherlock actor revealed he originally thought it would be "scary" to shoot the action blockbuster, fronted by Tom Cruise.
"I remember when I started on Dead Reckoning Part One last year, I saw all these big American actors and you just imagine they’re going to be really scary and razor-sharp. Then you realise they’re all s**ting themselves the same as anyone else!"
The actor went on to explain he had become close with everyone on set. He said: "I’ve made some really good friends on it, and it was a terrific experience. It’s not over yet! (Laughs.) It goes on and on and on – they sort of shoot in perpetuity.
"Because of COVID and shooting both Part One and Two back-to-back, it’s just been continuously rolling. Hayley Atwell said to me by the time she finishes, she’ll have been on both films for five years! That’s why everyone keeps looking young is because they were made years ago. "
Additional reporting by Sab Astley.
Horse-Play is currently running until 24th September at Riverside Studios – tickets are on sale now.
Mission: Impossible 7 - Dead Reckoning Part One will be released in the UK in July 2023. In the meantime, if you're looking for more to watch, check out our TV Guide or visit our Film hub for all the latest news.
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