She describes herself as a liberated woman, but Dame Helen Mirren admits she found it hard to play the passionate Catherine the Great.

The Russian Empress is famed for her affairs, and Sky Atlantic’s lavish four-part series focuses on her very physical relationship with Grigory Potemkin, played by Australian actor Jason Clarke. “Even though I think of myself as a liberated woman, I could not get my head around her sexual liberation,” said Dame Helen, “And I thought ‘You just have to think like a man, because men don’t have a problem with this'”. The 74-year-old actor was speaking after the UK premiere of Catherine the Great. She made a suitably regal entrance when she was carried down the red carpet in an intricate sedan char.

Dame Helen – who is famous for her starring role in The Queen – looked glamorous in wide legged dark trousers and peplum top with a diamond and topaz choker and earrings. Catherine the Great was made after Dame Helen announced in an interview that it was a role she’d like to play. The crew were allowed to film in palaces in St Petersburg at night – which delighted Dame Helen. “I am half Russian. When I am there I feel a connection,” she said.

The series is a sumptuous drama about power and passion. Asked what it meant to play Catherine, Dame Helen added: “I learnt that if women have the capability and the ability to work hard, they can do anything – including becoming Empress of Russia.”

All episodes of Sky original Catherine The Great are on Sky Atlantic and NOW TV on 3 October.