Remember when Doctor Who  was played by Eric Idle? Or how about the time it was Pierce Brosnan on a quest to find his father? Then there was the David Hasselhoff Doctor, with his trusty companion Pamela Anderson and a rapping time machine. Classic.
Rumours of Doctor Who movies roll round every couple of years and, generally, like the monstrosities described above, never actually happen. Most of the time, they don't even make it into serious development.
But there are two reasons to think this week's rumours have more truth to them. One is that they come from a plausible director, David Yates- he of the Harry Potter franchise. The other is the involvement of Jane Tranter, the BBC exec who did so much to bring Who back to TV in 2005. She, along with the lead writer of that version Russell T Davies, are now in the US trying to build the BBC's Hollywood business; this would seem to be an obvious project for her.
Just because something is possible, though, doesn't make it a good idea, and this is definitely not a good idea. Doctor Who is - I realise these points are obvious to the point of tedium- but they are key: British and a TV series. It is a spectacle of a kind designed specifically to be watched in the nation's living room on Saturday evenings, as an alternative to X-Factor or Ant and Dec. This explains so much about what makes the show fun; it's what allows cliffhangers and ongoing story lines, it's what makes it a shared cultural experience, something to be anticipated and tweeted and deconstructed. It's what allows the series to gobble up whatever bits of popular culture it fancies, and to turn them into monsters or silly jokes.
None of that would work in a film. You can't have ongoing stories or a nation watching all at once, clearly. But nor can you stuff it with the kind of silly gags that only make sense to those living on a single rainy European island. Can you really imagine a movie Who featuring Patrick Moore playing himself as a dirty old man? Or a version of The Weakest Link with a murderous robot Anne Robinson (the 'Anne-Droid')? In a movie version, kooky gags like that'll be the first thing to go.
But there's another less obvious reason why Hollywood and Who are mismatched. One of the reasons, I suspect, that so many literary or comedy types are unashamed Doctor Who fanboys is because it is a writers' series. It allows radically different scriptwriters to come in and offer their own take on the show without the risk of breaking it. How many other children's TV writers have become famous in their own right, like Davies or Steven Moffat have? How many shows have run publicity campaigns based on the status of a Richard Curtis episode or a Neil Gaiman one? Hollywood, however, doesn't think much of its writers. It's notable that a director is leading this, and one that doesn't seem too concerned that he has not gotten a script lined up yet; the writer, apparently, is just a detail.
Nonetheless, the show is probably still safe. A movie may conceivably make more money (although it would be one hell of a gamble), but in terms of the BBC's remit, and in giving it a centrepiece for the TV schedules, a TV series is far more valuable. That's good. A movie version of Who could quite plausibly miss the point of everything that makes the series worth having in the first place.