[The] existential spy is now an adolescent with neither the novel charm of his first years nor yet the old-homey familiarity of the detective hero. He is at the uncomfortable point where he seems repetitive without quite being traditional, and one finds oneself annoyed rather than reassured that the several parts of Horse Under Water could have been placed in or taken out of Deighton's other novels without changing anything important.

It is also true, without mattering much, that Horse Under Water was written and published in England in 1963 before either of his more celebrated books, and that no one thought it worth while then to publish it here. It has the same nameless, middle-class hero-spy who shall drudge for a living and be paid, and the same sort of tangled plot—intricate without being at all well-made—and the usual clutter of trivial detail that everyone finds remarkable whether the writer is Ian Fleming, John O'Hara or J. D. Salinger. Why shouldn't Deighton find it useful to throw in a chapter each about the techniques of deep-sea diving and the varieties of narcotics? He has to write about something, after all, and he is too honorable to pretend to be interested either in his cartoon characters or in the elaborate charades that they yawn their way through.