It's a long story, really. Somehow I stumbled across a Peruvian surf/psychedelic band called Los Silver Mornings, and one of their tracks ends with a few bars of the theme music from Midsomer Murders (here's a barely listenable version on YouTube).
So the interesting bit is that the woo-oo sound in the Midsomer Murders theme comes from an electronic instrument called the theremin. That much you may know, but have you ever seen anybody play one? I hadn't, and it's weirder than the sound itself. Here's the lady who's played the Midsomer Murders theme since the first series: