The Last Night of Henry Gascoigne's Life

Poiroh says the only logical deduction to be made from Henry Gascoigne's deviation from the norm regarding his food order was that he wasn't him. He writes a letter to his uncle on the afternoon of the 2nd November, but dates it the 3rd. George hunts about for the letter he has written, and shoves it in the pocket of his uncle's dressing gown. At 730 he is at the gallant endeavor, beard, bushy eyebrows all complete. Then a rapid metamorphosis in a lavatory,. Back full speed in his car to Wimbledon, and an evening of bridge. The perfect alibi. But the postmark on the letter. Oh