I've decided to use an ambulance siren as a jingle. I downloaded one from a free sound-effect site yesterday. Who knows? It could become as famous as Bill Cooper's air raid one! It would be put at the beginning and and of the programme and at the start and/or the end of segments of it.
What I need now is a female voice to say a few words over it. I'm going to ask on the HPANWO Forum. I might get my daughter to do it if she's willing.