In December 2004, Big Finish released the first of a series of UNIT-based audio plays, where General Sir Alistair Lethbridge-Stewart acted as a consultant to a new generation of officers and by series' end became UNIT's new Scientific Advisor. If the events in this series are to be reconciled with the books, these plays would seem to take place between the events of "The Dying Days" and "Happy Endings", as this version of Lethbridge-Stewart does not seem to be rejuvenated. Also, the public does not believe in existence of aliens, which would appear to place it before the events of "The Christmas Invasion".