Candid camera?

Channel 4’s Catching a Killer offered the rare TV spectacle these days of a middle-aged white male copper leading a murder inquiry. Then again, it was a documentary rather than a drama. In its resolutely sober way, it also proved a riveting one, if at times piercingly sad.

The programme followed the Thames Valley police as they investigated the killing of Adrian Greenwood in April 2016. The fact that Greenwood was an Oxford historian and book-dealer, and that the motive was the theft of a first edition of The Wind in the Willows, led one detective to suggest early on that ‘It’s like an episode of Morse.’ In the event, it proved a lot more straightforward, and a lot grimmer, than that.

Greenwood was found stabbed around 30 times in the blood-splattered hallway of his house, with the handle of a knife — although not the blade — close to his body. ‘It does appear at this stage that he has been attacked,’ explained senior officer Kevin Brown, clearly not a man to make any unnecessary assumptions. A post mortem also showed signs of torture. ‘Adrian had such energy and fire,’ said a female friend. ‘To think of him suffering like that… It keeps going through my mind.’

A scrupulous search of the house revealed that of all the valuable books Greenwood was offering for sale on eBay, the only one missing was that first edition of The Wind in the Willows, worth £50,000. But his phone had been stolen too, and by tracking its movements the police established that it was taken to Peterborough before being removed from the network. Now all they had to do was to use CCTV footage to find out which of the 5,000 cars that had been in Oxford at the relevant time followed the same route.