Graeme Swann

Graeme Swann was a cricketer who, in an altered 2008, was, according to The Times, "100 not out". The Fifth Doctor told Nyssa that this was evidence that the world had been changed — that it was a little bit better and more "perfect". (AUDIO: A Perfect World)

Behind the scenes
The joke here was quite topical, and would have made sense at the time of World's release in September 2008 — but not for much time thereafter. For several years before 2008, Swann had struggled in cricket, so the point of the joke was that a perpetually inconsistent cricketer finally found his form. In real life, however, Swann actually did find his form starting with a test match against India in December 2008, and went on to become one of England's best international players in the early 2010s.