Knox, Ronald - The Three Taps (1927) 

The three taps are gas taps; and the problem for Miles Bredon, ace investigator of the Indescribable Insurance Company, is whether their client Jephthah Mottram, gassed in his hotel room, has died through suicide, accident or murder. In favour of suicide we have the locked door, and the fact that Mottram is reported to have had an incurable disease (but why didn't it show up at the post-mortem? Points off for Knox there). In favour of murder is the open window and the fact that the gas had been turned off.

From this unpromising beginning Knox slowly weaves a complex web of motives and plots for the thoroughly nice Bredon to unravel, with the aid of his lovely wife Angela, gentlemanly Inspector Leyland and the charming Bishop of Pullford. Raymond Chandler would have loathed it. But lovers of the classic British cosy could hardly find a better example anywhere. Cluing is mostly fair, though the final conclusion is a little hard to take. Readers interested in Knox's life may find significance in the sympathetic portrait of the Bishop and his household, including the convertee Eames.

Jon.