"I was testing things like word length, sentence length, paragraph length, frequency of particular words and the pattern of punctuation," he explained. “What was striking about the tests was how often The Cuckoo’s Calling came closest to the texts by JK Rowling and it was closer to those than to any other crime novels. “In the vast majority of these tests I found that the new book came closer to A Casual Vacancy and/or Harry Potter and the Deathly Hallows than it came to the other six books by the other three authors. “The analysis corroborated quite strongly the hypothesis that had been put to me that she had written [The Cuckoo’s Calling]. “Given that there was some independent evidence - apparently - that it was written by a woman, I was comparing it with texts by three other women and certainly, of those four, I had no doubt that JK Rowling was far and away the most likely [author].