Jenna-Louise Coleman found out she had landed the role of Doctor Who's companion while she was in the supermarket.

The 25-year-old actress - who has previously appeared in 'Emmerdale', 'Waterloo Road' and Julian Fellowes' upcoming big-budget drama 'Titanic' - explained she was "holding an avocado" when she got the call and was too excited to be able to continue with her shopping.

She said: "I was in Marks and Spencer holding an avocado and having a debate about what goes best in a salmon salad when I got the call from my agent and it was kind of a bewildered excitement.

"All kinds of emotions. I was like, 'Really?' After that, I definitely couldn't continue shopping so I put down the basket and went for a little walk around and tried to digest it."

Despite her joy at bagging the coveted role - currently portrayed by Karen Gillan - Jenna-Louise struggled to keep her part in the BBC sci-fi drama a secret.

She added in an interview with BBC News: "I'm just beyond excited and I'm so pleased that the news is out because it's a secret I've been keeping for quite a while now.

"It's been so hard because I live in a house with three girls and then I've got all my friends who I went to school with, but the problem is when you tell one person you have to tell the next and I didn't know how long it needed to be a secret for. It has been very difficult."

Jenna-Louise - who beat hundreds of hopefuls to be named the Doctor's new assistant - will also enjoy the "huge privilege" of starring alongside current Time Lord Matt Smith in the show's 50th anniversary in November 2013.

She said: "All I can say is I had the most enormous ridiculous amount of fun in the auditions so the fact that I'm going to be working with Matt and Steven and the team day in, day out, is fantastic.

"It's a huge privilege. I am yet to hear what the plans are for the rest of this series and what storylines will take place but I'm very excited about that."

Jenna-Louise will make her 'Doctor Who' debut in the 2012 Christmas special.