Hooper alleges several flaws in experimental methodology, including gluing the moths in place on parts of trees where they would not naturally settle, feeding birds heavily enough to condition them to expect feeding at that point, artificially boosting recapture rates, altering experiments (unconsciously) to favour the expected outcome, and errors in statistical analysis.

Writing in Nature, Coyne (2002) attacked Hooper's "flimsy conspiracy theory [of] ambitious scientists who will ignore the truth for the sake of fame and recognition [by which] she unfairly smears a brilliant naturalist".

In Science, Grant (2002) critically summarised the book's content, saying "What it delivers is a quasi-scientific assessment of the evidence for natural selection in the peppered moth (Biston betularia), much of which is cast in doubt by the author’s relentless suspicion of fraud".

Bryan Clarke, who worked alongside Kettlewell at Oxford, described Hooper's book as "a treasury of insinuations worthy of an unscrupulous newspaper".

[6] Much of the work was published posthumously, the data being reviewed by a team of evolutionary biologists, leading to a vindication of Kettlewell's findings, the re-establishment of his reputation, and the restoration of the peppered moth as an exemplar of Darwinian evolution.