Roach: I couldn't turn Utopia down

Alex Roach has revealed she knew she had to star in new TV show Utopia from the moment she read the script.

The actress - best known for portraying a young Margaret Thatcher in Oscar-winning film The Iron Lady - plays Becky, a student framed for a serious crime in the new six-part thriller on Channel 4.

"I read all six episodes from start to finish which I've never done with a script before - it was so gripping I didn't even go to the loo!" she said.

"I had to have four rounds of auditions for this - it was more than getting into RADA! I cancelled a holiday and everything just because I wanted this so much."

On her very first day on set, Alex had to film a love scene set in a nuclear fallout shelter.

"You're nervous anyway starting a new job and then the schedule comes through and you're like, 'I'm doing a sex scene on my first day!'," she said. "We just had to get on with it."

:: Utopia begins on Channel 4 on Tuesday, January 15.