Donkeys years ago I was out on my Yamaha 250cc with my brother on the back of it. Nothing special you might think, well at the time the legal CC limit to ride with Learner plates was 125, but there was a loophole in the law that was exploited to the full that said you had a sidecar on the bike you could ride legally. I had my L plates proudly on show.
So my brother and I rode into Canterbury to go to the cinema when I noticed a policeman driving behind us on the ring road, naturally he followed us and waited until I'd parked and said "You are in soooo much trouble sonny." Long story short, he wasn't convinced by my polite explanation but didn't do anything further than say he'd get back to me. We went to the cinema and rode home afterwards and thought nothing more of it.
2 weeks later I'm working on my bike on the driveway when this same policeman pulled up, got out and sauntered down the drive then apologised for stopping me. To say I was shocked was an understatement I was just some snot-nosed kid and yet this policeman took the time to find me and apologise if he appeared to come on heavy that day (he didn't, but he did act smug that he'd nailed me). Anyway I spent a very happy 20min chatting with him showing him how the leaning system on this sidecar worked (it allowed you to lean the bike into corners like it wasn't even there) he was impressed and we both agreed it was a stupid law, because potentially a 17 year old learner could strap one to an XS1100 Yammy and wrap himself around a phone pole in no time.
Having witnessed that my attitude to the Police changed. Being civil with them initially helps enormously, because I imagine they have a pretty rough day dealing with the oiks.
See a picture below that I found on line of a Sidewinder sidecar. It was really handy for me having that sidecar to carry my carpentry tools in a box to and from work.