With her role in BBC One's lavish adaptation of Death Comes To Pemberley, Rebecca Front is fulfilling a dream, and, possibly, spoiling her Christmas viewing plans.

The three-part drama, which airs on consecutive nights starting on Boxing Day, falls short of being a classic BBC Jane Austen period piece, but it's the closest thing on the small screen this year.

Based on PD James's audacious sequel to Pride And Prejudice, it features Mr Darcy and his wife - the former Elizabeth Bennet - six years on from the original novel, plus the eccentric Bennet clan and the same cast of oddball aristocrats. Rather than merely revisit the much-loved characters, however, James's novel transplants them to an edge-of-your-seat murder mystery. "Takes some nerve, doesn't it?" says Front, laughing.

It also takes nerve to follow some iconic interpretations of many of the most famous characters in literary history. While her co-star Matthew Rhys has the unenviable task of filling Colin Firth's britches to play Mr Darcy, and Anna Maxwell Martin follows Jennifer Ehle and Kiera Knightley as Lizzie, Front is well aware that Mrs Bennet has also been played by some of the best in the business.

"I've always loved Jane Austen, and you can't not love the Bennet family, so it was a real thrill to be asked," she says. "It is both daunting and exciting. You have to quickly make the decision not to revisit previous versions, because I have seen Alison Steadman and Brenda Blethyn playing her. I had to put all that out of my head.

"I was so excited by the casting. Anna is just the most extraordinary actress, and Matthew Rhys is completely gorgeous but also cheeky, so he is perfect for Mr Darcy. Because the minute he starts to look austere, you know that mischievous quality is there underneath. It is a great cast - there's Trevor Eve and Penelope Keith as well. It is like a big box of chocolates that you can open and unwrap."

Having your character's backstory written by Jane Austen is, Front agrees, a rare treat. She also conspired with Doctor Who's Jenna Coleman - who plays her younger daughter Lydia - when deciding how to play Austen's reimagined manic matriarch. "You approach any comedy character exactly the same as you would a dramatic character, and try to play her as realistically as possible. You let the over-the-topness speak for itself," says Front, who remains best known as walking, talking omnishambles Nicola Murray MP in The Thick Of It.

"In Pride And Prejudice, Mrs Bennet is in a permanent state of terror about her daughter not getting married. Six years on, I wondered whether she would now be incredibly cool and laidback because her daughters are all paired off. But that isn't who she is. We decided she has gone from being terrified about her daughters' terrible looming spinsterhood to being scared that Lizzie's new house at Pemberley is too big, too grand, too frightening.

"The other handy thing is that on read-through day, I sat next to Jenna. I'd always felt that one day Lydia is going to turn into Mrs Bennet, so we talked about the levels of mounting hysteria within these two women and tried to mirror each other, pick up on a few of each other's mannerisms, which was fun."

It has been a longstanding ambition of Front's to appear in a costume drama. "I've been dropping enormous hints for many years - I've always wanted to get a corset on.

"When this came up, I thought it was exactly the sort of programme I watch at Christmas, so I thought I might as well be in it. Although now that I am, of course, I probably won't want to watch it."

Comedic roles were not always Front's plan, citing as her biggest influence Sir Alec Guinness, a man whose career showed it was possible to span genres. "I wanted to go into acting because of him. I was fascinated by that transformational quality. I remember seeing him in Tinker Tailor Soldier Spy when I was a kid and I couldn't believe it was the same guy from Kind Hearts And Coronets and The Ladykillers. That was the moment I realised it was all just acting.

"I had intended to be a dramatic actress. I went up to [Oxford] university, auditioned for lots of drama parts and got some of them - I did some Becket and a bit of Pinter.

"But I also auditioned for the Review, which seemed to be the course of least resistance, because not many women were auditioning. I realised there was a world of opportunity if you were willing to be a woman in comedy. So it was more of a pragmatic thing, that there was lots of work. It wasn't that I regarded myself as particularly funny. I still don't."

Casting directors and comedy writers clearly disagree. Next month marks 20 years since Front, alongside Chris Morris, Steve Coogan, Doon Mackichan, Patrick Marber and David Schneider exploded on to our screens in the groundbreaking spoof news show The Day Today.

"Oh gosh, that is frightening," says Front when I remind her. "We didn't know it was going to be so important or revered. You don't think in terms of people buying DVDs years later and still quoting bits at you - it was a chance to get on telly, play lots of fun parts and work with my mates."

Since that breakthrough, the 49-year-old has appeared in many critically lauded comedies. From the absurdist sketch comedy of Big Train, alongside Simon Pegg, Catherine Tate and Julia Davis, to various roles in Steve Coogan's Knowing Me, Knowing You With Alan Partridge - including a memorable Abba medley alongside Norwich's finest - via Davis's Nighty Night, Front has graced them all.

"There is a lovely self-conscious exchange in the last series of Knowing Me, Knowing You, where Alan Partridge is talking to me and Doon Mackichan, who are playing a couple of TV presenters," she says. "One of us refers to our show as being cult viewing, and Alan, as a sort of subtitle to the audience, says: 'Small viewing figures, carry on.' And that characterised everything I did for years and years and years. Cult television - small viewing figures. Carry on!"

The role that finally established Front in her own right, rather than as part of a comedy ensemble, was as Nicola Murray, for which she won a Bafta in 2010. "Prior to that," she says, "it had been a funny sort of career. I had worked solidly for years, but because I have done that cult comedy, small viewing figures thing that only pockets of people watch, no-one really noticed. So I was very excited to get a part in a show with momentum, that already had a great track record."

Such was the impact of the character that any MP who displays a particular lack of talent - see sports minister Helen Grant's recent inability to answer a single question about sport - is compared to Front's fictional version. "I know, I slightly wish they would hurl it at some of the male MPs as well," says Front, "because Nicola isn't useless because she's a woman, she's useless because she's useless.

"It does get thrown around a lot, though, and because of the show I have met a lot of politicians and ex-politicians. It is interesting, they all love the show - or at least watch it - and quite a few female ministers or ex-Cabinet ministers have taken me to one side and said: 'It's me, isn't it? All my colleagues reckon Nicola Murray is based on me.'"

Not that her role alongside Peter Capaldi meant she knew in advance that he was to be cast in Doctor Who. In fact, even her mother beat her to the news.

"I am so excited - I will definitely be watching on Christmas Day," she says. "I couldn't believe it. I was in America when it was announced and my mum texted to say Peter was going to be the next Doctor Who, and I replied rather grandly, going: 'I don't think so, Mum, it is just a Twitter rumour.' She came back with: 'No, he is on The One Show right now!' "I sent him a congratulatory text. He will be fabulous, what a great choice - and he is working with lovely Jenna, so what could be better?"

Perhaps Front joining them in the Tardis? "Oh, I would love to, that would be fantastic," she laughs. "But it is not on the cards at the moment."

If they do want Front to appear, they might have to book her well in advance. In the last year, Front has appeared in no fewer than four new comedies - suffragette sitcom Up The Women, historical therapy sketch show Psychobitches, comedy thriller The Wrong Mans and healthcentre sitcom The Spa - as well as Grandma's House. She's also had a guest role in Poirot and a regular role in Lewis, which has come to an end.

"There's been a whole range, it has been great," she says. "I was the straight woman in Psychobitches, and then a completely Grand Guignol pantomime character in Up The Women. I've had a ball.

"One of the nicest things was doing Psychobitches - it was an almost entirely female cast, and they were nearly all people I had worked with in the past. It was lovely. I sat in a comfy chair in a nice cardigan waiting for my mates to turn up - Julia Davis, Sarah Solemani, who I met on The Wrong Mans, Jo Scanlon, Frances Barber. It does feel like a family sometimes."

She may have worked with many of the modern comedy greats, but her wishlist still contains two very big names. "Two of my great heroines are Victoria Wood and Julie Walters. They were the other reason I wanted to get into the business," says Front. "Victoria Wood's writing is fantastic, and Julie Walters is just a supreme actress - she can play the most extreme parts and somehow make them totally credible. There is real heart to her, a real warmth in her acting."

The breadth and range of TV comedy seems to be expanding, with The Wrong Mans - written by and starring James Corden and Matt Baynton, and fusing hapless buddy comedy with action thriller to great effect.

"That is absolutely what is going on, and it is very exciting," says Front. "What is brilliant is that they crossed all the genres, taking it right away from being just a comedy or just a thriller, and turned it into something that is genuinely funny and genuinely thrilling. There used to be far more limited styles and also far more limited opportunities for women.

"So when you get a real range of comedy, which we have had in the last couple of years, and also a real range of opportunities for women - which we have also seen this year - then that does make you feel hopeful for the future."

Asked what is driving that change, particularly in terms of a long overdue expansion of roles for women, Front has a simple response. "I hope the message is finally getting through. Maybe a new generation of people are coming through to whom it has never occurred that women can't be funny," she says.

"It literally hasn't dawned on them that women can't be funny, because clearly they are.

"There are still not enough good parts for women and there still aren't nearly enough women on panel shows, so there is still work to be done. But it is so much better than it used to be."

Somehow, in between all that filming, Front has also found time to write a book. They asked her at a weak moment, she claims. Not an autobiography "because that would be quite dull", instead it is a series of short, funny stories based on her life - a comedy memoir, perhaps - that she hopes to have finished by Christmas.

"I've deliberately avoided anything that smacked of a theatrical anecdote," she jokes. "Hopefully it is funny, it is meant to be funny - it has been really good fun writing it.

"But I will be quite happy to get back to filming, doing the day job again, in January. I have enjoyed writing, but it is quite solitary. I mean, that's glaringly obvious, but when you sit down and do it, you suddenly realise, 'Oh - I'm just alone in this room for days on end,' whereas I am used to being around loads and loads of people and having a laugh. So I am keen to get back to being in an ensemble of nice, loud actors." n

Death Comes To Pemberley is on BBC One on Boxing Day, 8.15pm; December 27, 9pm; and December 28, 9pm.