Pauline Collins made her name below stairs as maidservant Sarah in Upstairs, Downstairs. Her latest TV role finds her climbing the social ladder to play a woman who is very definitely an "upstairs" person - Queen Victoria.

She features as the monarch in the second story of BBC1's new Doctor Who series, Tooth And Claw, in which the queen meets a werewolf.

Nearly four decades ago the actress appeared in the series opposite Patrick Troughton's Doctor in a six-part story, The Faceless Ones.

"Obviously it's much more hi-tech now, and I did absolutely adore Patrick Troughton. He was a wonderful doctor," she says. "We were one of the rare episodes that didn't have Daleks. Our story was about aliens who inhabited human beings, which was quite advanced for its time."

She's also revealed that she could have become a more permanent feature of the series as she was asked to become one of the Time Lord's travelling companions. She turned down the chance because she didn't want to be tied to one role for a long time.

Despite her liking for Troughton's Doctor Who, she has only good things to say about the role's current occupant, David Tennant. "Having seen him in action, I believe he's going to be the best Doctor ever," she says. "He seems to combine authority and humour and quirkiness which, in a way, is an amalgam of all the very best Doctors. He's terrific in it."

Praise indeed from the actress who won awards on stage and screen as frustrated Liverpool housewife Shirley Valentine. She also has nice words for Russell T Davies' script for Tooth And Claw, and his depiction of Queen Victoria.

The Doctor and Rose encounter the monarch in 1879 in the Scottish Highlands on her way to Balmoral. A band of warrior monks and the werewolf ensure this is an episode of Doctor Who that Collins herself found scary.

"Victoria is a great character and one of the things that Russell has done is to give her a little bit more humour and humanity than perhaps she's known for," she explains.

"Certainly in Mrs Brown, with Judi Dench, you saw the humane side of Queen Victoria, but this is great. And she's also a person of great authority which she manages with humour as well."

For her, it's the limitless possibilities of Doctor Who which give the series such enduring appeal, with different things for different people. "One of the great things which Russell has really taken up in this reincarnation of Doctor Who is that once you unleash the imagination of writers, it can go anywhere, anywhere in the universe," she says. "He's kind of set us off on a rocket into the universe in a way. That's the appeal and that's why it's timeless. It can catch up with whatever is available to us scientifically, or in our imaginations, whatever the era is, and then you know in 50 years time it could still be working in cahoots with whatever science is available at that time."

One challenge of filming was the lack of a werewolf to act with, as it was added later using special effects. But the actors did have two performance artists to demonstrate the movements that the werewolf would do.

"Occasionally, we had to literally work to a green screen and a dot on the horizon, and one of the problems about not knowing exactly what you're acting against is to do too much," she says.

"We were reminded by the director to remember perhaps how you would be in that situation, and one of the things that fear does is to almost paralyse you."

Then there was the dilemma of playing a real person and coping with the Queen's heavy costume. "There's always a problem with playing real people - I've actually played several real people in life but none as high profile as this one. People have an idea of how she should be," she says.

"Certainly the costume is just wonderful and makes you inhabit the character more. It's really well designed and that particular Victorian look is great. It was the heaviest costume I've ever worn. It was like carrying several small children round with me."

She's no stranger to costume drama, from Upstairs, Downstairs to her more recent role as the eccentric Miss Flite in BBC1's adaptation of Dickens' Bleak House.

"One of the nice things, I suppose, about growing older - and particularly about the two lovely parts that I've played, Queen Victoria and Miss Flite - is, in a way, I seem to be easing into grandma state," she says.

Working in a room filled with birds as Miss Flite seems to have been less problematical than an imaginary werewolf. "I particularly loved working with the birds," she says. "They were amazing. I've worked with all sorts of animals in my life and these birds were perhaps the best trained creatures I've ever worked with. They were fantastic."

Doctor Who: Tooth And Claw is on BBC1 at 7.15pm, tonight.