11 questions (and some answers) we have after Doctor Who series 10 episode 1

Is the Doctor going to regenerate early?

A new trailer for the series is the second to show Peter Capaldi’s Doctor starting the regeneration process, and this time we see that golden light around his entire body, not just his hand as before...

But does this mean a new actor will be taking over the role from Peter Capaldi sometime during this series, rather than in the Christmas special as we've previously been told?

Read our thoughts on the matter here...

When is the Master coming back?

During the same trailer that appeared to show us The Doctor regenerating, we were also treated to a glimpse of John Simm’s unmistakeable bleached-blond Master. Sure, the news of his returned leaked a couple of weeks early, but it's still got plenty of fans asking: when will the rogue Time Lord re-materialise?

Well, he could be back for one episode, he could be back for two or even three, but either way you're likely to have to wait a few weeks for that Master-Missy team-up – here's why...

What are The Doctor and Nardole guarding in the vault?

Whatever The Doctor is hiding in his mysterious vault under St Luke’s university in Bristol, it’s hinted to be a source of great danger or significance (after all, he stuck around for 70 years to guard it) and we’re sure we’ll find out the truth of what’s inside in weeks to come.

At the moment, we’re theorising, amongst other things, that the Gallifreyan-looking symbols on the door could hold the key – after all, we already know two versions of evil Time Lord the Master are returning. Read our full thoughts here.

Is Nardole an android?

When we next meet him assisting the Doctor in the opening episode of series 10, Nardole seems to have got his body back – but the squeaking joints and occasional dropped nuts and bolts give the game away. It seems pretty clear to us that the Doctor has saved Nardole's head and placed it on a robot body of his own invention. And a pretty good job he's done too, even if he does have a few screws loose...

Did the Doctor take those pictures of Bill's mum?

Early on in the episode, Bill reveals to the Doctor that her mum died when she was a baby and that, despite being told that she looks a lot like her, she doesn't have the photographs to prove it. Then, Bill's foster mother suddenly finds a box of photos in the back of the cupboard. "I didn't know we had these," she says.

Looking through those old pictures of her mum is an emotional moment for Bill – even more so when realises where they really came from. Reflected in a mirror in the background of one of the snaps is the unmistakable face of the 12th Doctor, squinting into a camera. Being able to do kind things like that for your friends is just one of the perks of owning a time machine.

What was that song playing when Bill and Heather met in the bar?

At that fateful, heady moment when Bill and her star-crossed would-be lover Heather lock eyes in a bar, the track playing in the background is Joy Division's ethereal rock anthem Love Will Tear Us Apart – a prophetic choice for a couple whose intense connection is the very reason they can never be together.

Who were those aliens fighting the Daleks in the Time War?

During Bill's inaugural adventure through time and space, the Doctor and his new sidekick got caught in the crossfire between the Daleks and an army of pink-armed, dreadlocked aliens. Just who were they? "It doesn't matter!" was the only answer The Doctor offered. However, we've got the lowdown on classic Who foes the Movellans.

Have we seen the last of Heather?

After a hectic chase through space and time, Bill finally said a sad farewell to the girl with a star in her eye, giving up the chance to travel the universe with a puddle of super-intelligent space oil in the shape of her former crush (yep, this is why we love Doctor Who). But could Heather (played by Stephanie Hyam) return at some point in the future?

"I don't see how," said The Doctor. But when Bill looked longingly towards the blue box in the corner of the room, it was a clear reminder that those who travel in the Tardis have access to "everything that ever was or ever can be". Steven Moffat is leaving but what's to say that another showrunner won't one day decide it's time to catch up with Heather. It might be nice to see how's she's getting on.

Why did Heather turn into a Dalek?

On one hand, mimicry seems to be the space engine oil monster's forte. On the other hand, until it came face to face with a Dalek, we'd only ever seen it transform into Heather, the idea being that it had taken on her form – and her final instructions not to leave Bill – when Heather was absorbed into that sentient puddle round the back of the university. Its one drive was to find Bill and give her the chance to travel with it. So why did it transform into a Dalek?

One answer is undoubtedly that Steven Moffat thought it would be pretty cool for the stellar "defect" in Heather's eye to appear at the end of a Dalek's eye stalk and give her identity away. Another is, that despite Heather being the creature's Pilot, it was still capable of mimicking other things. After all, it repeated word for word everything anyone said to it. Perhaps taking on the form of a Dalek was a defence mechanism prompted by being shot by one. Or perhaps that damaged the Heather-creature, momentarily resetting it so that it then mimicked the first thing in front of it. Certainly, the Heather-Dalek's slurred speech suggested it wasn't on top form after being hit by a volley of Dalek energy bolts.

How long has The Doctor been at the university?

During this week’s episode Bill suggests that The Doctor has been working at St Luke’s university for at least 50 years, possibly as many as 70, with the Time Lord presumably there all that time to protect the mysterious vault that will seemingly form much of this series’ central mystery.

And if the Doctor really has been in the one location for this entire period it could explain why he’s been keeping such a low profile. After all, if he did go out and about into the world, he’d probably end up running into every incarnation of his former selves as they adventured through the 20th and early 21st centuries. Definitely not worth the hassle.

Is this the snowy scene that was rumoured to be from the Christmas episode?

Months ago, we heard reports that Pearl Mackie had been spotted filming a snowy scene that many assumed at the time would feature in the 2017 Christmas special. But it turned out the episode hadn't been written back then, let alone started shooting.

It now seems likely that what they saw were the shots in which Bill traipses into university to deliver a Christmas present to The Doctor in the opening episode.

Doctor Who continues on Saturdays on BBC1