Doctor Who will be getting more celebratory treatment with a BBC TV film about the beginnings of the long-lasting British sci-fi show, starring Harry Potter actor David Bradley.

Bradley, best known for his role as cantankerous Hogwarts caretaker Argus Filch, will play First Doctor's actor William Hartnell in An Adventure in Space and Time, part of the BBC’s 50th anniversary celebration of Doctor Who, The Guardian reports.

Brian Cox will play Sydney Newman, BBC’s then Head of Drama, and Jessica Raine has been cast as Doctor Who producer Verity Lambert. Both people’s names were used for a love interest of the 10th Doctor, played by David Tennant in a two-part revival series in the 2005.

The 90-minute drama is being written by Mark Gatiss, who has written several episodes of the series. It is being produced by current Who showrunner Steven Moffat, who took over from Russell T. Davies in 2010, and exec producer Caroline Skinner.

“It’s a lovely story about very fascinating characters,” Skinner said. “There are lots of witty and entertaining stories about the genesis of Doctor Who which say quite a lot about what the early ‘60s in Britain was like. But it’s also a very personal story about William Hartnell and Verity Lambert and their relationship being forged in the making of what turned out to be a sensational hit show that we’re still watching today.”

BBC America, co-producing with BBC Cymru Wales, will air the film in the U.S later this year, according to Entertainment Weekly.

The network also will air on March 30 the second part of the sci-fi’s seventh series, starring Matt Smith as the TARDIS-traveling Time Lord's 11th incarnation.

It could be interesting to see Bradley also make a crossover appearance into Doctor Who’s actual 50th Anniversary Special this year being written by Moffat, as Hartnell himself passed away in 1975.

William Hartnell's first episode as the Doctor, "An Unearthly Child."