Dame Helen Mirren has said she was “scared” and “frightened” by her new role as Catherine the Great.

The 73-year-old actress – who stars as the titular Russian queen in the Sky Atlantic drama – described the show’s creator’s decision to write the part for her as a “terrible mistake”.

Speaking at the BFI & Radio Times Television Festival, the veteran actress explained that a pair of producers she had previously worked with had read an interview in which she had mentioned wanting to play the powerful monarch.

BFI and Radio Times Television Festival
Dame Helen Mirren with one of the costumes from Catherine the Great (Isabel Infantes/PA)

She said: “I made the mistake when I was doing an interview and someone said, ‘what would you like to do next?’ Maybe it was after Elizabeth.

“I said, ‘Well, I’d quite like to play Catherine the Great, actually. That would be an interesting character’.

“People heard that, producers David Thompson, who was involved in Elizabeth, and Charlie Pattinson – and they went off and raised the money.

“It’s really bad. I was, ‘oh no, that’s a terrible mistake’. But then I was committed. I couldn’t wriggle out of it.”

BFI and Radio Times Television Festival
Dame Helen said the part of Catherine the Great had worried her (Isabel Infantes/PA)

Dame Helen, who also starred as Queen Elizabeth II in The Queen, said being responsible for kick-starting such a vast project had worried her.

“I think I was nervous. I think was frightened,” she said.

“I don’t know why but I was. You set yourself up to fall flat on your face. I’ve always been very wary of saying ‘I’d like to do this’, because it is a recipe for disaster.

“It’s better to allow things to come randomly and brilliantly.”

The Oscar-winner’s induction into the Radio Times hall of fame closed three days of panel discussions and talks at the festival.

Dame Helen as Catherine the Great in the Sky Atlantic drama (Sky/PA)
Dame Helen as Catherine the Great in the Sky Atlantic drama (Sky/PA)

Dame Helen also defended Catherine the Great against claims of promiscuity and that she had had sex with a horse.

She said: “That was calumny thrown at her by history because history doesn’t like very successful, very powerful women.

“They have to drag them down and history tried to drag Catherine down. I hope we are going to reinstate her reputation as the incredible leader that she was.

“I’m not saying she didn’t have her faults. She made mistakes and finished up quite tyrannical but she was originally a reformer and a Westerniser, if you like, of this vast, vast country.”

Catherine the Great is set to air on Sky Atlantic this autumn.