Many Golden Age detective novels, with their engrossing puzzles and attractive backgrounds were a comforting read - particularly after the horrors of the Great War. The murders often left the bumbling police without a clue but some aristocrats and Oxford graduates found them a piece of cake to solve.
Meanwhile, real life was painting a different picture. Guns were left over from the war and many men were familiar and hardened to the results of using them. There was a surplus of women - so if a man tired of his wife, the mainly male juries would turn a blind eye until a judge began to notice.
Suffragettes, Communists, overworked and underpaid coal miners and the IRA were anxious to rearrange the world and were prepared to use bombs or burning barrels of oil, and criminal gangs were running riot in their fast cars whilst the police had no such vehicles with which to stop them.
Add some real-life murders: the Field Marshal war veteran shot dead on his doorstep by a one-legged ex-squaddie, the dying shopkeeper who refused to name her attacker, the star of cowboy films acting his way out of suspicion, the mother killer checking beforehand that her insurance was still valid, the poisoning wives juries would convict, the Potteries murder, where the wrath was turned on the Scotland Yard detectives sent to help, and the exhausted fleeing murderer, caught at last, asking, 'Can I have a banana?