The Case of the Housekeeper's Hair(1948)
(Book 32 in the Ludovic Travers series)
A novel by Christopher Bush
"Believe me or not," said Ludovic Travers to his old friend Superintendent Wharton of Scotland Yard, "I have an idea that a certain man is going to commit murder. He told me so--in so many words." Superintendent Wharton gave a prodigious grunt, and hooked on his spectacles. (They were nothing but plain glass, Travers decided.) "What was he? A lunatic, a crank, or what?" "As sane and sober as you and me," replied Travers. "He's young, intelligent and wealthy---as far as we're allowed to be. And he treated the whole thing so cynically and casually that I'm all the more sure he was serious." And that's the beginning of The Case of the Housekeeper's Hair. If Travers hadn't been so sure the man was serious, he mightn't have gone snooping.
Used availability for Christopher Bush's The Case of the Housekeeper's Hair