Doctor Who fans have another wild theory about Thaddea Graham's Bel

And though we're desperate to know what happens to Jodie Whittaker's Doctor next week, there were plenty of other unanswered questions to ponder, too.

Thaddea Graham's Bel, who is pregnant, and Jacob Anderson's Vinder are the main subplot of this season, with the lovebirds desperate to reunite.

Last week, fans had wondered whether Bel and Vinder were the Doctor's parents after Bel told Vinder he looked "different", suggesting he could be in the process of regeneration. This week, however, another fan posed an even more far-fetched proposition – what if Bel is the Master in disguise?

The theory was posed by a Doctor Who fan on Twitter, and it's all to do with Bel being a title for some Babylonian gods - we told you it was out there - but it prompted many replies on who Bel and Vinder's (potentially timeless) child could be.

Some commented that they thought Bel and Vinder could be the Master's parents instead of the Doctor's, as previously speculated. Some went as far as to suggest that not only could Bel be the Master, but she could also be the Doctor's mother – which would be the biggest twist in the series' history.

Of course, these are just rumours, and highly unlikely ones at that. But it's certainly fun to consider the possibilities – and their repercussions for the future of the series.