Doctor Who: Why is everyone always so bad at predicting the next Doctor?

Every single time we start talking about who the next Doctor should be, people invariably start suggesting names so absurd and unlikely that you have to wonder if they’ve recently returned from a parallel universe, where appearing in a popular British sci-fi series is the pinnacle of creative and financial achievement.

Tilda Swinton? Richard Ayoade? Idris Elba? If people seriously think these sort of names are realistic, they haven’t been paying attention to the way the show is made, or its demands. It's like watching the judges on The Masked Singer confidently predicting that Brad Pitt has decided to dress up as a talking clock and sing ballads on ITV primetime – while technically possible, not a suggestion that anyone could really take seriously.

Look, starring in Doctor Who at all – let alone as the Doctor – is a great opportunity for plenty of actors, a tremendous chance to reach a younger generation of viewers and a performance challenge that would appeal to many. What it isn’t is a dream job for absolute every actor, everywhere in the world, no matter what else they’re doing.

For example, the current bookies’ favourite? I May Destroy You’s Michaela Coel, who made waves last year with her self-penned comedy-drama dealing with sexual assault. Coel is a great actor, and would undoubtedly make a great Doctor – but there’s no way she’d walk away from a creative and artistically vibrant boom in her own career (having endured a close-fought battle to control the rights to her stories) to lock herself into 10 months a year filming other people’s scripts.

The same goes for the apparently 8:1 joint third contender Richard Ayoade, a man who has successfully flitted between deadpan presenting, sitcom acting roles and directing indie films, and who it’s hard to imagine trading in a wry public image and hugely successful career for the Dalekanium handcuffs role of Doctor Who.

It reminds me of when speculation was rife that Phoebe Waller-Bridge was in line to be Chris Chibnall’s next Doctor (a rumour which has returned this year). Maybe she was once on a shortlist somewhere, who knows? But anyone looking at the stratospheric success of Fleabag and Killing Eve, her increased retreat behind-the-scenes on various shows, big-money roles in blockbusters like Solo and general upward trajectory really should have asked themselves – would she have given up that creative freedom, that implied future success, to be in Doctor Who in 2016?

I don’t think she would have – and indeed, she didn’t. Just like any number of Hollywood stars like Tilda Swinton or Idris Elba, who have been rumoured over the years largely just because they’re interesting names, and not because there’s any plausible reason for them to become the Doctor.

That’s the best way to think about future Doctors, after all – what would that actor do? If you were in their shoes, would Doctor Who be a brilliant opportunity and the role of a lifetime, or a frankly bizarre pitstop in an otherwise very different career? Would it be an ingenious next step that would offer new challenges, or would it be a step away from the work you’re truly passionate about?

It’s a mistake to look for big, buzzy names who’ve recently done well in another drama, or for massive stars who definitely wouldn’t be able to commit to the punishing schedule. It’s also wrong to think vaguely in your head of actors who you think are a bit “Doctor-y” in their public image – because frankly, that doesn’t mean they’d create a great Doctor onscreen.

The right thing to look for? Well, I’m going to do something risky now and make a prediction. If I’m wrong, and Tilda Swinton does start filming in Cardiff later this year, feel free to send me snarky tweets.

OK, here goes – the next Doctor will almost certainly be a British character actor, who has probably booked a few good TV roles and has some recognition but hasn’t necessarily had one defining role that made them a household name – or, if they’re an up-and-comer, hasn’t had the time to do that yet.

They’ll be someone for whom Doctor Who is a step up, a role that challenges them and that they’ll grow into, rather than something that they could do in their sleep. They won’t be the obvious choice, but the sort of person who’ll make you go “huh, OK, yeah I could see that actually.”

Obviously none of this really matters, the bookies’ odds are always pretty much nonsense (at least to begin with), and this’ll all fade away once we find out who the next Doctor is. And in a way, it’s a compliment to Doctor Who itself that such wild casting theories are so regularly espoused. You don’t get people suggesting Harry Styles should be the next Death in Paradise detective, or that Chris Hemsworth is in line to join Line of Duty’s AC-12.

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Only Doctor Who has a central role so unusual, so iconic that it can seem plausible that anyone in the world would go for it – even though the truth is, as it always has been, that the next Doctor will almost certainly be someone a little more down-to-earth.

Doctor Who returns to BBC One later this year. Want something else to watch? Check out our full TV Guide.