The Saint and Scotland Yard by Leslie Charteris (Pan, 1951)

THE SAINT VERSUS SCOTLAND YARD (originally entitled The Holy Terror), tells how Simon Templar relieves crooks of their ill-gotten gains and, while thus helping Chief Inspector Teal of Scotland Yard, at the same time receives a fair proportion for himself and his girl assistant Patricia Holm.  Part I tells how he settles accounts with a professional blackmailer and murderer called the Scorpion and is thereby enabled to pay his income-tax.  In Part II he foils a giant currency swindle, but incidentally leaves a dead man and other casualties to be explained by the exasperated Teal.  In Part III he confronts two diamond-smuggling gangsters after a murder in a train ; Inspector Teal butts in and is fooled, while the Saint takes one of the gangsters on a wild car-ride ; Teal is finally checkmated on the great liner Berengaria and is left to open a strangely filled trunk labelled with his name.

The copy on the back cover of this book is so exhaustive it reads more like a synopsis than a blurb!  The Saint vs Scotland Yard is comprised of three loosely-connected novellas, in which Simon Templar foils the villains and the law, and escapes with the loot.  And his "girl assistant"?  Actually it's made clear that she is his live-in lover, an arrangement that is common today, but must have raised a few eyebrows back when this was written.

No wonder "The Saint" series became so popular.  The character must have been so much fun for respectable and law-abiding citizens to identify with!