Anthony Gilbert 
Treason in my Breast [EPUB ebook] 

It’s often the ordinary people who spot the murderer – whether they know it or not… Classic crime from one of the greats of the Detection Club’Few murders would go unhung, ’ said plump, cynical Arthur Crook, 'if people used their eyes more. It’s the man selling violets in the gutter, the woman exercising her Pekinese, the chap reading the midday racing news in the Tube who actually have the chance to spot the murderer. They’re the people he can’t guard against.’Arthur Crook is a delightful nosey-parker, and here his blustering humour and bulldog tenacity face their toughest test yet.