Each year's prize is no doubt influenced by the year before's, but more than influence, there's a faint sense of actual trolling here. The 1960 winner involved faked industrial espionage, rendered airily and unconvincingly; the 1961 winner involves real industrial espionage, rendered in convincing, concrete detail. I learnt a lot more about pottery than I had expected, and ended the book with a faint desire to buy fine china. The espionage strand of the plot is woven with with a murder strand, with the relation between the two unclear for a fair part of the book. Both strands are of fine quality, resolved satisfyingly. Characters are well-written, often identifiably human, not just contrivances of the plot. The Staffordshire setting is terrific. The final few pages are really excellent, downbeat in a very unexpected and very welcome way.
So all in all, you can see why the novel won an award, and it's got a lot going for it. But the accolades in the introduction to my copy—"masterpiece", "one of the finest British stories about a private investigator"—strike me as rather hyperbolic.
The first point of demerit is the writing, which has a tendency towards the purple and some peculiar passages in which the author seems to exhaustively test out a stylistic device---for example, three pages where five of or eight paragraphs begin with a single-word sentence. The narration is first-person, and I suppose one could attribute all this to the clever capture of a slightly pretentious voice, but I rather think that the author quite likes their narrator, and reckons the prose does him a favour. I'm not sure it does.
The second point of demerit is the relentless appraisal of women's appearances, by the narrator, other men, and other women. It's not just that they're all evaluating looks all the time; it's also that they're all drawing ridiculous inferences from appearance to character. There's even a bit of meta-judging, where the narrator makes judgements of some other men's characters on the basis of their judgements of women's appearances (and whether their judgements accord with his). I suppose this again could be very clever writing: a woman accurately capturing the way in which male gazes imposed verdicts on women in that time and that place, in the cause of undermining the power of that gaze. I don't much doubt the accuracy of the description, but I do doubt the emancipatory intention; again, the author seems to like the narrator, and it's the narrator whose judgements we hear about most often, in most detail. Also, women get blamed for a lot of things in this book. Really a lot.
All in all, I think this one is excellent if you're prepared to credit the author with a sophisticated dislike of the narrator, and fairly good if you're not. I'm not.