Dear Steven Spielberg: To the film director planning Dr Who, The Movie: please don't mess with the Daleks' plungers, and if you give the Doctor a West Coast accent, you may be E-X-T-E-R-M-I-N-A-T-E-D.

You are taking on a sacred trust. You plan is to make a Hollywood film about Dr Who and the Daleks, use the original storylines but make them more frightening and give the baddies greater hi-tech powers.

I guess that over in Universal Studios, where ET has ridden a bicycle and a tyrannosaurus has fought with a diplodocus, it must seem a small matter to have a Dalek climb stairs. Alas, no.

Daleks are very British monsters.

I'm sure there may well be protests at your initial script meetings that anyone can escape a Dalek by nipping upstairs or sneaking up from behind and tying a bit of cloth over its eyepiece. I know Indiana Jones would find it hard to believe, but in 30 years that never really occurred to us. In our nightmares, we were always trapped in a corridor - British sci-fi is big on corridors - face to face with a demon about to atomise us with a flash from its metal midriff.

Your script executives might also have problems with the Dalek's other piece of equipment, the thing next to the eyepiece that looks like a plunger. The comedian Eddie Izzard speculates in his act that a Dalek in a good mood might decide not to wipe out the planet but clean the toilet instead. As I say, it's a very British sort of monster.

Most of all, there is the voice. Vibrating its fearsomely enunciated orders of global destruction to unquestioning underlings, it has given more children over here nightmares than the most carnivorous dinosaurs. Steven, no disrespect, but we Dr Who-watchers cannot contemplate a Dalek with an American accent any more than we can contemplate a tanned, rugged, West Coast 'Doctor'.

Disney may model Aladdin on Tom Cruise, but allow any of the brat pack to play our most revered mad scientist and you will never be forgiven. Of your former players, the eccentric boffin in Back to the Future might just do, but it really ought to be a Brit. Sean Connery, perhaps, could conjure up the right blend of absent-minded intensity. But how about one of our television doctors? None of them Hollywood stars yet, but they know the timelord territory.

Actually, I'm afraid American audiences are going to have trouble with the Doctor. For a start, there's not a whiff of romantic interest. In 30 earth-years of travelling through time and space and battling with Daleks, Thals and Cybernauts, he has never encountered a pheromone. And Daleks definitely can't have sex, unless that thing wasn't for cleaning out the toilet after all.

The Doctor doesn't even have a winsome child, son, daughter or grandchild that he can resolve his relationship with between Cybernaut attacks. All very unspielbergian.

But don't lose interest. If anyone can take Dr Who through a multi-million budget movie and out again unscathed, it's you. Just allow us our British eccentricities: monsters that can travel through time and conquer galaxies but have to take the elevator to the second storey. Get it right, and you'll win an Oscar. Get it wrong and, in a parlance you will shortly become familiar with, you will be exterminated.