Helena Bonham Carter has revealed she struggled to remember if she was playing the Queen Mother or a witch - as she shot two films simultaneously.
The actress and mum-of-two was starring as the wife of King George VI - played by Colin Firth - in The King's Speech. But at the same time Helena was shooting Harry Potter And The Deathly Hallows, playing evil witch Bellatrix Lestrange.
She told of her balancing act as she spoke ahead of Thursday night's premiere of The King's Speech at the BFI London Film Festival.
Helena said: "Actually my son, who was six at the time, said 'Mum, do you have to be the witch or the queen tomorrow?' And I said 'That's a good question, as long as I don't get that mixed up.'
"I had the teeth for the witch so it was slightly different gear. Having said that, the witch Bellatrix is exhausting because she's very screamy and a bit of a hooligan so it was quite nice to have the weekends off - kind of, as the queen, as she's a bit more restrained."
The Harry Potter star admitted there was pressure playing a real life character and as well as reading biographies, she did once meet the late Queen Mother.
She revealed: "I did meet her. I think she came to the premiere of A Room With A View when I was very young, all those centuries ago.
"She had this great grace and she was great at being gracious and she always had that sort of cloud of charming vagueness, but I think underneath it, having read about her, she had a huge amount of inner strength."