Nicholas Lyndhurst was cast as Gary Sparrow, a TV repairman whose marriage to Yvonne is in the doldrums. Out in London looking for a business address one day, he wanders down an alley, Duckett's Passage, and finds himself - though of course he does not immediately realise it - in the London of 1940. In a street-corner pub, which at first he mistakes for a 1940s themed hostelry, he meets Phoebe, the landlord's attractive daughter, and they are immediately smitten with one another. Returning through the same alley brings Gary back to the present, and he discovers that he can enter 1940s London the same way at any time. So begins his double life.