As much as the formulaic stories, I find Midsomer Murders to be the repository for both the very early performance today's established actors, and the late-in-career performance of actors way past their prime. Similar to the 1980's and 90's American Murder She Wrote, and I suspect Angela Landsbury had a lot to do with the selection of the older actors who were her early career peers. Her friend Hurd Hatfield turned up several times at the very end of his career, for example.