The man who regenerated Doctor Who

The final episode of the this series is on BBC One this Saturday

He's installed aliens in Downing Street, sent witnesses to observe the end of the earth and trained the Daleks to run upstairs.

It takes a brave man to make changes to a BBC institution - and the author Russell T Davies has certainly pushed the boundaries.

He's the main writer behind the revival of the long-running BBC children's drama, Doctor Who.

The series comes to a dramatic end this Saturday night, as the Doctor and Rose - Christopher Eccleston and Billie Piper - come face to face with a space station full of Daleks.

Natasha and Dermot spoke to Russell T Davies this morning.

Russell T Davies, writer of the new Dr Who series

Russell said that taking on the series was a little scary as it is such an iconic programme but of course it's been a great success, attracting a wide range of viewers.

"People who think they don't like science fiction are watching"

And he praised the cast, for their part in making the programme so popular, saying that Christopher Ecclestone's decision to get involved early on in the project made a huge difference to the show.

Doctor Who began its life in the black and white days of the early 1960s. Played by William Hartnell, the doctor was less a space buccanneer than an elderly gentleman in search of intergalatic tea and biscuits.

One innovation in the series was that - when a lead actor wanted to leave - the doctor simply regenerated into a different person.

Over the years, the Doctor has had many different personalities - but none quite so driven as the current Doctor, Christopher Eccleston.

Eccleston has already said he wants to leave at the end of this series - so the one thing we do know is on the cards for the Doctor is another change of personality.