This website is often asked what the theme music to this show is. It's "Small World" by Scottish singer-songwriter Roddy Frame. It is available on his album Surf (track three)
The title is reference to a British slang phrase which refers to customers who arrive at the pub in the afternoon just (or sometimes even before) the establishment re-opens its doors for the evening.
If you listen to Phil and Nige's police radios carefully, you can sometimes hear swearwords being spelt out in alphabetic code. This was an in-joke created by the writers.