Graeme Harper on location for The Unicorn And The Wasp. Vicky: If you could direct a one-off special Doctor Who, where it's a crossover with any other TV program, which programme would you pick ...

This episode guide is made up of the text of The Discontinuity Guide by Paul Cornell, Martin Day and Keith Topping, and Doctor Who: The Television Companion by David J. Howe and Stephen James Walker.

Graeme Harper: I was really excited as I knew it could really be brought to life with all the technology available now. I did not expect to be thought of, as I am considered part of the old school.