I flew in to Ascot a few years back on an AOC charter. The company I was contracted to believed that another one of their machines was liable to be used for an illegal charter to Ascot by a self-fly hirer. They had informed the CAA who were there as a matter of course.
Sure enough the heli arrived and 3 pax got out in their Ascot finery. They were asked how they knew the pilot and they said they were all friends and all paying their own way.
The pilot (dressed in a white shirt and black trousers) was interviewed after he'd parked and gave the same story.
He then sat in the pilot area all day chatting to those he knew whilst his "friends" enjoyed their day. The man from the CAA joined us at lunchtime and didn't ask a single probing question.
Later he took his PAX, sorry friends, back to their house in the country before returning the machine.
IMHO if you're an honest individual / company that inadvertently breaks the rules you're much more likely to face a grilling from the authority than those that systematically flaunt the laws.
Unless you're willing to hand the CAA a smoking gun with a fingerprint on the trigger they know they might not win in court and so nothing will happen.