What could David Bradley be talking about? In a session at the London Film and Comic Con, the actor who plays the First Doctor in this year’s Doctor Who Christmas special talked about a scene from the episode that he says left both himself and departing Twelfth Doctor Peter Capaldi close to tears – and that somehow came as a surprise to them.

It apparently involves some unexpected events that took place around them as they were filming, which seems pretty unprecedented in the world of scripted TV, and makes it sound as if they deliberately had a surprise sprung on them.

What it might be who can say, but the fact that the special is likely to end with Capaldi’s farewell and regeneration and perhaps Bradley’s as well means something emotional isn’t too much of a surprise – but the fact that they didn’t know it was coming certainly is.

What can it all mean? Here’s what happened in David Bradley’s own words, so you can judge for yourselves…

“There’s an event towards the end of [the Christmas special] that happens and when it happened, well, we just did a take and neither Peter nor I expected it.

“There was no CGI involved, it was all happening and we were both almost blubbing by the time that the take ended. I can’t say, I’m not going to say, what it was but it was quite an event and we weren’t prepared for all the things that were going to be going on around us as we were doing our dialogue.

“And as I say to you, we got quite lumpy. They’ve kept that out of the trailer but it takes it all to another dimension…”

A multi-Doctor episode, a regeneration, the introduction of the first female Doctor, a farewell to Peter Capaldi – and now this. It’s pretty clear this is going to be a very special episode of Doctor Who – and it’s going to get emotional…

David Bradley was speaking at the London Film & Comic Con