To be fair, the Police are fairly good in South Wales.
I saw their last speed trap yesterday afternoon in Cardiff. As you approached in either direction, there were about three marked Police cars and bikes clearly visible at two ends of the road. So to speed past these youd have been nuts anyway. Then in between these two sets of cars, about a 1/4 mile further, there was a big Transit van with big cameras and yellow reflective stuff everywhere. If you got done by this sort of speed exercise then you were clearly not observant enough to drive, let alone speed!!
There are a few normal Gatsos in Cardiff, but again youd have to be blind not to spot them.
On the M4 theres another Transit/Fiat van mobile unit that sits atop bridges between Cardiff and the Severn Bridge. But the van is red with big slogans saying "THINK! SLOW DOWN!". Again, get done by these and youre being a bit silly.
If you got to the South Wales Police website, you can navigate to a section that tells you the location of every permanent camera - and where the mobile ones might be situated.
This sounds like heaven compared to some regions!! I actually think its a far better approach, especially in terms of community relations. If theres a gathering of cars in Cardiff (not a cruise), then the Police usually come over for a chat, satisfy themselves that youre a bunch or reasonable car enthusiasts - and then go off to catch any of the nutters/theives that there might be. And Im happy to pay tax for that!