1. The Doctor’s parents (Human Nature)
Fans can be forgiven for still feeling sad about John Smith and Joan Redfern, the couple that never were after the Doctor transformed himself into a human with no memory of who he once was. However, the pair ended up embodying another very important pairing in Who history: the show’s original producer Verity Lambert and co-creator Sydney Newman. First off, in Human Nature, it’s revealed that John Smith’s ‘parents’ were called Verity and Sydney. A lovely touch. If that wasn’t enough, though, when the Doctor revisits Joan’s great-granddaughter (who looks suspiciously like Jessica Hynes once again) in The End of Time, her name, it transpires, is Verity Newman. Rather sneaky, but also rather sweet.