You learn something new every day. I’ve only just discovered that all the titles in Faith Martin’s detective series include the word ‘narrow’ because she herself lives on a narrow boat. It’s obviously no coincidence that the heroine of the novels lives on a narrow boat too, moored at Thrupp.

As Lewis and Hathaway leave our TV screens, possibly for ever, it’s good for us Oxfordites to know that there is another detective mind addressing the multitude of fictional murders that occur in and around our city.

Faith Martin’s detective is Hillary Green, who now features in her 12th book: A Narrow Margin of Error (Robert Hale, £19.99). By now, Hillary has retired from the police force and is working as a civilian consultant to her former colleagues in Thames Valley Crime Review Team. She has been called in to help crack the ‘cold cases’ – unsolved, historic homicides A Narrow Margin of Error is perhaps the narrowest margin that the former Detective Inspector has had to face. Initially, it’s a tad predictable – yet another cold case, the interviewing of all the old suspects, and the expectation that this superb detective will at last solve the puzzle. This time the murder file is more than ten years old – the victim being a young Oxford student, whose active social life alienated him from rather too many people to make for a short suspect list.

But there the predictability ends and the pace hots up as Hillary has picked up a stalker. We, the readers, are well aware of the stalker’s identity, but Hillary is dangerously ignorant, and this provides a parallel, spooky strand to the murder case, with an unexpected turn of events. Worth reading – but perhaps too unsettling if you live on a narrow boat yourself.