The Expert was a BBC TV series that ran from 1968-76, starring Marius Goring. I loved it at the time. Oddly enough, Bernard Knight doesn't seem to have been involved, albeit he was by some distance the leading forensic pathologist of the period. He wrote this novel about Professor John Hardy in 1976, the year of the fourth and final series. He orginally wrote it under the pseudonym Bernard Picton, and I wonder if he contributed to the TV series under that name.
Well, it's not up to the standard of the TV show. Hardy seems weak, which he never was in the series. Admittedly his wife Jo has just been killed (the climax of series four?), but even so - Hardy is meant to drive the drama but here he doesn't. His findings are attacked and it is only intervention from his new assistant Price that restores order. It doesn't work. It is two stories uncomfortably sandwiched together and neither particularly well resolved. It is poor and I won't be squandering more of my time on the so-called 'Sixties Mysteries'. I will focus purely on Knight's later creation, the medieval Coroner or 'Crowner' John de Wolfe, which are great.