The first thing I wanted in this story was to acknowledge Rose as a character, but not necessarily have her as a part of the action. Having made her pregnant with Time Lord twins rather incapacitates her as a character. She really can’t take too many TARDIS trips, and she definitely shouldn’t be in the firing line.

So the idea of a planet that it one big health spa, where The Doctor could leave his pregnant wife to relieve some of her aches and pains came to me, and I created Anchoriss, where service is an honour that is given only to the best and brightest. That isn’t a very important detail, since the story isn’t about the spa and its people as such. But I wanted to contrast, in particular, with the Ood and their slave mentality and low status.

But the main part of the story is about The Doctor and his students. The important statement is the one about the TARDIS becoming a training TARDIS again after a millennia. I don’t remember exactly which documentary about Doctor Who somebody mentioned that the TARDIS was for training purposes and should have had as many as six people flying it, but that seemed such a logical idea that I incorporated it into a lot of stories as the reason why The Doctor sometimes has trouble with it.

Three of the students have been introduced before. Marton Pallister is the Tiboran boy who has The Master’s DNA due to some creative stuff in a fertility clinic – more of which will be seen later. Dale Sutton is the Human who infiltrated the Sanctuary looking for a news story and stayed to become a real student. Tony Chandler is the Human with strong psychic powers who featured in Chris’s first meditation class. Darryl Harvey wasn’t featured before. She is one of the Gallifreyans that The Doctor rescued from the Sontarans, and all that matters for the moment about her is that she is an attractive young woman (65 is young for Gallifreyans) and she and Dale have a bit of a thing going on.

The Doctor as a teacher is something that has been hinted at down the years on TV and in books. There have been the occasions when he has posed as a teacher to solve a mystery – three times in the David Tennant era, of course. But also, the relationships between the Fourth Doctor and Adric, and the Seventh Doctor and Ace were very much master and apprentice. To some extent, the Third Doctor and Jo, though she was much more of a surrogate daughter. In recent years his companions have not allowed him to be the boss so much. Rose, Martha and Donna all stand on their own two feet, and rightly so. But bringing him back to what he does best and is happiest at – nurturing young minds – was the object of this story.

The ‘leap of faith’ in the mist was an idea that came to me simply to hold off for a little longer on meeting the water ‘spirit’ which is the pay off of this story. Having the students, especially Dale, the least certain one, learn to trust him like that was something that might pay off in later stories if he should need a group around him that would explicitly obey his instructions without thinking or questioning. The ‘leap of faith’ motive, though, was one I was able to reuse later, and may well be used again.

It also, of course, gave Dale and Darryl a chance of another intimate moment, cementing their relationship.

Yes, of course, there is a ‘homage’ in the way the water spirit appeared to them all. Yes, completely lifted from The Abyss. Well, why not? How many people have sat through that long and sometimes tediously talky film for the two scenes of sheer magnificence – the alien communicating with them in the water and the alien ship rising up at the end. The alien ship rising up has been outdone now by Stargate Atlantis, but nothing beats that scene with the extruded water forming a shape and communicating with the Humans. This was an attempt to recreate it in a less hostile environment and make contact with an entity of pure good that even The Doctor felt humbled before.

No action as such in this story. Just sheer descriptiveness. This is something you can get away with in text that the TV episodes would never allow. It was a joy to write.