Any sense of prurience is relieved by Mr Kahr's prose, which is sympathetic, witty and erudite.

ECONOMIST: Sexual fantasies

The guts of the book are to be found in the final chapter, where Mr Kahr answers the 21 questions he poses at the outset.

ECONOMIST: Sexual fantasies

Kahr explains that 25 people (who are based in the customer loyalty department) help manage the account, with one person at a time driving the conversation.

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Mr Kahr, a London-based academic and therapist, surveyed (anonymously) 18, 000 people in Britain and America in conjunction with YouGov, an internet pollster, and conducted 132 five-hour interviews.

ECONOMIST: Sexual fantasies

But Mr Kahr focuses on nasty experiences in the past.

ECONOMIST: Sexual fantasies

The upshot is that nine out of ten people have sexual fantasies, mostly pretty lurid ones and Mr Kahr thinks the remaining tenth are crippled by shame, guilt or repression.

ECONOMIST: Sexual fantasies