The story of Doctor Who's origins is steeped in legend and meaning... it is also a story that touches on the history of television in general and the BBC in particular. A program that would appeal to a family audience while challenging their intelligence and entertaining them as well, Doctor Who was inspired by the pulps but blazed its own trail as well. Historical, fanciful, exciting and humorous, Doctor Who is a TV series unlike any other.

On its 50th anniversary, at arguably the peak of its international popularity, the story of Doctor Who will be told.

The initial cast from 'An Unearthly Child'

The initial cast from 'An Unearthly Child'

Doctor+Who+filming+at+the+BBC(Via TardisNews)

Radio Times is chuffed that Mark Gatiss is calling his drama about Doctor Who's birth An Adventure in Space and Time. This was the tagline RT printed on the billing for episode one in 1963 and indeed on all 253 editions in the 60s. For Gatiss, the 90-minute special (filming now and due to air in November on BBC2) is "quite simply a dream come true". He describes it as "the story of how an unlikely set of brilliant people created a true television original".

David Bradley (Argus Filch in the Harry Potter films) is playing William Hartnell, the actor who was initially reluctant to take on the role of the mysterious time traveller. He soon fell in love with the character and was sad to leave in 1966. He died in 1975. Bradley says when Gatiss offered him the part, "I almost bit his hand off." Our first picture of Bradley in character shows him on the second day of shooting last week, with Lesley Manville as Hartnell's devoted wife, Heather.

Call the Midwife star Jessica Raine has been cast as producer Verity Lambert (then just 27), while Brian Cox (the international film star, not the prof ) is playing the "father" of Doctor Who, Sydney Newman, a flamboyant Canadian who was BBC head of drama.

The only surviving member of the quartet who created the series is Indian-born director Waris Hussein. He's helped Gatiss with his "meticulous research" and is delighted to be a key character in the drama. "I am to be portrayed by my doppelganger, Sacha Dhawan, a handsome actor. Vanity prevails!" he jokes. Recently seen in Last Tango in Halifax, Dhawan was one of the original History Boys (in the play and movie).

Filming began on 3 February at BBC Television Centre, on what is likely to be the last drama made on the site before it's redeveloped. Executive producer Caroline Skinner tells RT: "As the BBC moves out of TV Centre, we are moving the cast and crew for An Adventure in Space and Time in! It's a fantastic opportunity to film this momentous story in the actual location – a little bit of television history."

Get exclusive Doctor Who postcards – free with this week's Radio Times magazine.

So... anyone in the UK gonna get me those postcards?