It's Doctor Who's 49th birthday – or to put it another way, just one year until the show's long-awaited 50th anniversary. And what better way to mark the occasion than a look back at the Time Lord's debut, on 23 November 1963, in the very first adventure An Unearthly Child.

Here, concerned school teachers Ian (William Russell) and Barbara (Jacqueline Hill) trace their pupil Susan to a junk yard, where they encounter an eccentric and uncooperative white-haired gentleman (William Hartnell). But what's that blue (well, dark grey box) in the corner – and where is Susan...?