As we enter the final furlong of this book, my notes are getting briefer and briefer (which, for many of you, will be a relief!). But Episode Six turns up two of the most important, for me, aspects of the book that were the main raison d'etre of its existence. Firstly, at the very end we see the heroism of Mike Yates come into play, justifying his later promotion and, more importantly, we introduce the Vault.

As a lad, I always was concerned about what UNIT did with the left-overs from alien invasions etc., and although it's taken until this chapter, we are finally at the crux of the story. I always intended this to be a trilogy of stories (the sequels ultimately being Business Unusual in 1997 and Instruments of Darkness in 2001) but had no idea it'd be spread over five years - I thought I'd manage one a year!

The ongoing story of the Pale Young man, the Irish Twins and the blond assassin, plus assorted hangers-on such as the Stalker were all intended to be Third Doctor stories. Then, as I mapped things out, I realised that what ultimately became Instruments would have to be a later Doctor, preferably the Sixth. But after doing Scales, Virgin didn't want what I wanted - i.e. Business Unusual to be a Third Doctor/Sarah Jane/Jeremy Fitzoliver story.

Indeed, as their licence to do Doctor Who ended shortly afterwards, it couldn't happen that way. And in conversations with BBC Books, it was made clear that they wanted a Sixth Doctor/Mel book quite early on, so Business Unusual shifted to that era. With Instruments wrapping it all up, I lost the natural time lapse that Season 11 to Season 23 would have given me (to allow for the characters of Trey and Joe to grow up and the Irish wins to seek redemption) and also the Jeremy Fitzoliver backstory. But what I gained (the chance to write for the Sixth Doctor and Mel twice) more than made up for that. But I digress...