I was speeding while overtaking a coach on a duel carriageway. Going past a junction, a police car started up it's sirens. I slowed down instantly, and was also approaching a roundabout. I looked in my mirrors but I couldn't see them heading my way, so I carried on going and took my intended exit. They made no attempt to follow me or pull me over as far as I can tell.
It's clear I've done wrong by speeding, but I wasn't sure how to tell if they wanted to flag me down, or the coach (which was also speeding). It is possible that the siren was unrelated (there's a big public event today), that it was used as a warning, or that they already got my details (though it all happened very quickly).
That's all happened now. How should I handle it in the present moment?
Arrows unrelated, but yellow car would be the police car.
Ignore it. They probably don't have enough evidence to prosecute. They can't just eyeball your speed, they have to accurately measure it according to some very strict rules. If by some chance they do have sufficient evidence, you'll just get an FPN in the post.
If the overtake of the coach was obviously unsafe and it happened in full view of the police car and it had video equipment fitted and running, they might have sufficient video evidence to prove careless driving. You'd probably be looking at 3 points and a £100 fine. Unless you forced the coach to brake hard or you were driving like an absolute headcase, dangerous driving isn't on the cards.
>>4156 is almost certainly right - if you didn't annoy them enough for them to chase after you, they're not going to bother filling out the paperwork.
If you ever see little white squares or circles painted on the road in places, apparently they're to give a reference point to help police calculate speed from video footage.
>>4163 If the distance is known, they can be used on the in-car systems to corroborate the reading or if they're unable to keep a constant distance. Or, on a motorway, by an officer in forming his expert opinion.