The Betrayer is – as the cover sticker says – the inspiration for the Netflix series LEGENDS. I don’t have Netflix, so I haven’t seen the show, but a lot of the publicity turns around how Stanton (played by Tom Burke) was plucked from HM Customs and Excise airport baggage searching, given two weeks training, and sent undercover with the drug gangs. Whether that reflects the series or not, The Betrayer shows that Stanton had a more paced progress from admin, through airport anti-smuggling, local VAT control and Collection Investigation Unit, onto the Investigation Division. But it’s true that, when Stanton is asked to apply for a new undercover team, “we had no undercover training course of our own, so I had to pick up tips from colleagues who had done it in the past.” There is some fascinating detail about HMCE’s varied attempts to develop undercover training, before settling on the police SO10 course and Greater Manchester Police’s Henri Exton, who had devised his own psychologi...