Broadchurch star Olivia Colman joins Oscar-winning actress Vanessa Redgrave in BBC2’s haunting one-off psychological drama, The Thirteenth Tale (Monday, Dec 30). Here she talks stunts, scares and how she struggled to keep the biggest TV secret of the year!

Can you tell us more about Margaret Lea, your character in the The Thirteenth Tale, and how she gets involved with telling Vida Winter’s (Vanessa Redgrave) story?

“Vida approaches Margaret to be her biographer. We don’t really know why she’s chosen Margaret, but it soon becomes clear that Vida knows something about Margaret’s own past and she taps into that upset. She’s fearless I think. When Margaret’s past is revealed, it’s clear she’s felt like she’s had to toughen up. And she’s functional. She’s not girly or glamourous, she’s tougher.”

It sounds like Vida and Margaret want to find out about each other really. Do they form a bond?

“Yes. Margaret’s not sure why she’s taken this job, but she can’t leave once she starts to hear Vida’s story. Margaret is also carrying around a kind of ghost with her and Vida says: ‘Let it go, it will ruin your life.’ It’s through hearing Vida’s story and watching how she’s suffered with things all her life that Margaret realises she’s right and they have a lovely bond by the end.”

What is the significance of The Thirteenth Tale?

“Basically, Vida’s written a book called The Thirteenth Tale, but when you read it there are only 12 tales. The Thirteeth Tale is the most important one: it’s the story of HER life, and she’s saved this story to tell before she dies.”

How did you feel about working with Vanessa Redgrave?

“Working with Vanessa was one of the things that attracted me to this. I was really excited, yet really nervous. I kept waking up in a sweat thinking: ‘She doesn’t like me!'”

We see Margaret having to climb through windows and suchlike in this drama… do you enjoy doing your own stunts?

“I do get a real rush of adrenaline. For the first take of that scene, I was a bit nervous and looked a bit like a fraggle running, so we had to do it again. I think Margaret’s very brave – I certainly wouldn’t clamber around a dilapidated old house, crawl through a window, hear a dragging body sound and go towards it.”

The Thirteenth Tale is rather spooky. Do you scare easily?

“I am a big chicken! On Broadchurch, Jodie Whittaker and I were flatmates and one night there was a horror film on… I had to go for a wee with the door open, I was so scared. Things like Tarot readings are not my bag at all.”

Broadchurch was one of the TV success stories of 2013. Why do you think people were so drawn to it?

“It didn’t patronise anybody and there was something about Broadchurch that didn’t just concentrate on the case, it was everything… all our nightmares… and it featured normal families that don’t want to think about that awful thing happening. You’ve got to watch the fallout of that lovely community crumbling. It was awful to watch and fascinating at the same time.”

What was it like having to keep arguably the biggest TV secret of the year: Who Killed Danny Latimer?

“I just had to stay at home, not answer the door, and not look anyone in the eye. I’m good at keeping secrets, but I knew I could just twitch at the wrong moment and give the game away.”

You also won two BAFTAs this year for your roles in The Accused and Twenty Twelve. Where do you keep your awards?

“You know how really cool people say they keep them in the downstairs loo? Well, I’m really uncool, so they’re on the fireplace! I don’t party all night so, after the awards dinner, me and my husband snuck off home, where I had a cup of tea and put my big socks on.”

You’ve been hailed as the next Judi Dench. How does that feel?

“It’s lovely that someone’s put our names together in the same sentence because I think she’s amazing. She’s always worked and she’s deliciously private – she’s everything I admire.”

Finally, The Thirteenth Tale will be going out at Christmas. Do you like Christmas?

“I love it! I get really excited for months beforehand about Father Christmas coming… and sitting by the fire… I put on my Christmas CD in November. I’m a bit of a fascist about weekend mornings and I tell my kids that, if it’s before 8am, you read or go back to sleep; after 8am we can all play. But on Christmas morning I’m the one shouting: ‘GET UP!!'”