These dramas have another virtue you rarely find elsewhere: they are unafraid to show middle-aged love. Most television wants beautiful stars, particularly beautiful  young women stars. The hero can be older and uglier, but his private life is invariably a mess, allowing him to seduce a new woman in every episode. By contrast, Inspector Barnaby in Midsomer Murders is happily married and Lewis has had a rather touching love affair developing between the widowed inspector and a police pathologist. Whereas television usually goes from first meeting to seduction in 30 minutes, here the writers have spread the tentative romance over several series. Death in Paradise follows a similar pattern. It has a comic relationship building between the strait-laced English detective and his beautiful sergeant from the Caribbean.

The easy thing to say is that British television is just updating Agatha Christie, the most successful mediocre writer there has ever been. They recreate her "Mayhem Parva" to use the crime writer Colin Watson's happy description of the Christie school of village detective fiction, and over-complicated plots. The result, however, is not quite as benign as Christie would have wanted.

If the British public and a slice of the international audience want to see murders set among the English upper-middle class they also want to see the English upper-middle class murdered. The people in Midsomer Murders are rotten, almost without exception. It is not just the murderers. The victims usually deserve their punishment, and the supporting characters are just as bad. In the last episode I saw, elderly aristocratic parents did not care about the death of their son. His bereaved wife at once tried to seduce a rich neighbour for his money, even though the neighbour, a pathetic wimp, was already married to a woman who came across as a demented sexpot. You only have to see an Oxford don in Lewis to know that he is either a corrupt scientist illegally experimenting on human guinea pigs or an amoral intellectual who preys on his female or male students (and sometimes both). Meanwhile the guest stars of Death in Paradise play the English at their worst: the type of expat who provoked the subject populations of a quarter of the world to anti-colonial revolution. The pleasure of viewing Georgian rectories and Oxford colleges accounts for a part of the appeal of English crime, but so too does anti-intellectualism and class envy.

Along with Dr Who, they are the most popular middlebrow dramas Britain can make. I do not wish to knock them — how can I when my own weary eyes turn to them? But it is a shame that we cannot do better. In the second half of the 19th century, when the Germans had Wagner and the Italians had Verdi, we had Gilbert and Sullivan: clever, satirical, undemanding and safe. As opera was then, television drama is now: the most interesting art form of the age. Once again, the English don't want to exploit its full potential.