On the topic of police cars having cameras to scan number plates...
I bought a somewhat-tatty X1/9 (it was a 'bodged'-tatty rather than 'neglected'-tatty, if you know what I mean... paint was shiny but loads of filler in every panel)...
...A week or two after purchase, I was driving it along a fairly busy road and turned off onto a sideroad, a road I would drive quite often over the years. To my amazement, a police car swung into the road behind me and turned its lights on. I couldn't believe that I'd been speeding or anything, so I got out and stood placidly beside the car. The female cop came around and checked the registration ('tax') and WOF ('MOT'), which were both fine, and took a cursory look inside. She said, "That's fine Sir" and I was allowed to drive away.
Speaking to the previous owner about this rather harrowing experience, I discover that he had been stopped during a police roadblock (happens from time to time, particularly public holidays) and found to have expired WOF/reg. Also he had an unpaid parking fine.
I think the moral is clear. I have never been stopped 'on speculation' like this, and I hope that I never am again. I suspect that there is some kind of central 'blacklist' of likely targets? So how to avoid the embarrassment? Keep your MOT/Tax/WOF/Reg/insurance/whatever up to date...
Cheers,
-Alex