Trending: Who would be best on Doctor Who?

Time Lord casting news - Rebecca Armstrong wishes they'd think outside the Tardis

Joanna Lumley, Jessie J and Helen Mirren (PA; Getty Images; Rex Features)

Doctor gets new assistant' isn't the sort of headline that would normally make you look twice, unless you're a particularly avid reader of NHS staff mag YourChoice. But when the professional in question is Doctor Who and the assistant will be helping him save the universe rather than the group practice's budget, telly addicts and sci-fi fans alike rear up to get a better view.

The latest Tardis co-habiter was named yesterday as former Emmerdale actress Jenna-Louise Coleman. Young (25), attractive (twice nominated for Sexiest Female at the British Soap Awards) and with a solid acting background (she's been in Waterloo Road, Captain America: The First Avenger and will be bobbing up – or perhaps down – in ITV's new take on Titanic), Coleman seems to be a perfect fit for a role that has, in recent series been, well, all about being well fit.

The recent series of Doctor Who have, after all, seen hot doctors (Christopher Eccleston, David Tennant, Matt Smith) assisted by companions so foxy (Billie Piper, Freema Agyeman, Karen Gillan) that it's a wonder any of them have time to fend off the Cybermen when they're navigating will they/won't they plot lines. Even the rumours surrounding the 12th Doctor (despite the fact that the current incumbent, Matt Smith, is still very much at the helm of the Tardis) named thinking lady's TV totty Benedict Cumberbatch, although speaking to the Radio Times this week, Who writer Steven Moffat poured cold water on that theory (and on hot-under-the-collar fans).

I think that all this Doctor/assistant sexual tension is obscuring the elephant in the room – the issue shouldn't be sex with the Doctor, but the sex of him. Or her – as, despite inching closer to the possibility of a female Doctor by way of Donna Noble, River Song and the much-missed Sarah Jane Smith, we've yet to see a Time Lady take up the sonic screwdriver.

"We've seen female Time Lords before – the Doctor's companion Romana in the Seventies was one," explains Tom Spilsbury, editor of the monthly Dr Who Magazine. "There's no reason why the writers couldn't do anything they wanted and Doctor Who has a format that means you can do all sorts of things."

My money would be on Helen Mirren as the next Doctor – and she agrees, having told the Daily Star in December: "I would like to play the new female Doctor Who. I don't want to just be his sidekick." But what would die-hard Whovians think? "I think it's a tough idea to make work. There would be a lot of resistance to it," says Spilsbury.

But fellow expert Simon Brew, editor of the website Den of Geek thinks otherwise. "I think there'll be one one day – I think there should be," he says, before revealing that, technically, Doctor Who has regenerated as a woman before. "Joanna Lumley appeared as the Doctor in a spoof four-part series for Red Nose Day called Doctor Who and The Curse of Fatal Death in 1999." Lumley! Another great potential Doctor who, as with Mirren, brings some much-needed maturity to a role that has been played by steadily younger actors since the marvellous, silver-tressed John Pertwee.

But this being the 21st century, I probably wouldn't be allowed to cast either of my Doctors without a little bit of chemistry between them and their helpmeet, much as I'd like Doctor Who to be more about the monsters than the romance. So may I suggest Harry Styles as a bright, young companion to either of these excellent candidates? OK, so Styles might be a bit on the busy side, what with a number one album Stateside, but he's be easy on my sci-fi eye.

Or perhaps we should take a leaf out of Torchwood's book and get bisexual Jessie J to spice up life in the Tardis with Helen or Joanna.