Full Circle I was originally drafted by Simon, my partner, who wanted to have a go at writing a Time War story. He never finished it, so I took over, working on the idea of the twins, Chris and Davie, wanting to prove themselves as Time Lords by doing what The Doctor had never done – return to Gallifrey when it was still there. The row with their mother, David accusing The Doctor of putting ideas in their heads, and their attempt to break the protocols was all there as a template to build the rest of the story upon.

That they could do so when The Doctor himself never could is proof that Davie Campbell has become a very smart young man who knows a lot about temporal engineering. Chris as his second in command does as he tells him but it is Davie who pilots the TARDIS and knows what to do to make it go beyond the limits. He has the ambition to do so.

Davie is, in short, a chip off the old block, very much emulating his great-grandfather. But that doesn’t mean he won’t be in trouble when his great-grandfather finds out.

As if he isn’t in enough trouble already.

The full consequences of what they did are dealt with in the next story. Here, we deal with the emotional impact for The Doctor and David of the rebellion by the two boys. David and The Doctor have always had issues between them about the twins, who had developed such a close relationship with their great-grandfather that their father felt left out of their lives. But the one thing they do agree on is how much they love the boys and desperately want to find them.

The Doctor says nothing to them about what happened. But he knows how to read the TARDIS database. He knows what happened and when. And he understands something very big and momentous now.