Mad Men star Jon Hamm has revealed he was asked to audition for BBC period drama The Tudors - after being mistaken for Scottish actor John Hannah.

The US heartthrob, soon to star in Channel 4's Black Mirror Christmas special, said he was asked along to try out for the historical romp after being confused with his almost namesake - known for his roles in Rebus and Four Weddings And A Funeral.

Hamm, 43, said it was a "100% true story" and explained: "I went to an audition for the Tudors and they thought I was John Hannah. I'm not Scottish, I'm not 50, I'm also not eligible to work in the UK. But I did learn a bunch of lines and practised the accent."

However, he decided not to go forward with the audition after it became clear there had been a case of mistaken identity.

"They asked, 'do you still want to do it?' I said, 'No, because there's no point in it. I'm not going to get the job'," he said.

Hamm has been cast in the latest Black Mirror film, created by writer Charlie Brooker, playing a pick-up artist and psychological manipulator.

Brooker has actually worked with Hannah on his detective spoof series A Touch Of Cloth and, joking about the casting of Hamm, he said: "We thought we were getting Hannah again."

The feature-length episode, White Christmas, weaves together three narratives, which Brooker said was "a selection box for Christmas".

The film - which also stars Rafe Spall and Oona Chaplin - takes some inspiration from the idea of "blocking" people on social media, creating an alternative reality where people who have been blocked means they show up as grey blurs in real life.

Brooker argued that while this might be pleasant for the length of a Tube journey, there is a darker side to blocking.

"There's no way back, the conversation has ended, it's not like you can build bridges," he said.

"I'm on Twitter but I don't tend to block people unless they are unrelentingly unpleasant."

Brooker also revealed his creative process for Black Mirror: "I think of the worst thing that could happen and then I write it down."

:: White Christmas will be screened by Channel 4 at 9pm on Tuesday, December 16.

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