Fast jet pilots don't break the rules - they make them. (Spears inbound!)
Phil_R, if you want to know what jet guys do then PM me and I'll get you up to have a look around the Sqn, maybe talk you through flight planning issues, show you how we do everything we can to avoid upsetting the public etc. Once we lose the low flying areas, we'll never get them back.
And yes, you can see high vis vests in the mach loop.
Flying below 250 ft is incredibly demanding and can be sustained for only short periods of time - areas are allocated for this purpose (Operational Low Flying areas). I've never known of a pilot to fly around continuosly at less than 250 ft without authorisation, he knows the boss would tear him apart for it and that he is also likely to be killed.
Hope that helps.