I also happen to think that speed cameras (with automatic number plate recognition and ticketing) are probably one of the most effective ways of enforcing any speed limits.

The technologist in me (but not a specialist in this particular field) has been amazed for some years that no version of camera seems to have yet been developed that's legally watertight (i.e. prosecutions or fixed penalties have a low rate of successful challenges), and more economic than road humps of any sort. I don't share the privacy concerns about them - unless we go down a path that leads to drivers having a right to be anonymous and remove number plates, on roads that are public shared places.

The 'smiley face' device does seem to be a fairly effective compromise. They are easily portable (they just need a mains power take-off from a street lamp) and I believe the one that was in Perry Rise has now been moved. If they recorded the speeds measured over a period that would be a good way of monitoring effectiveness - but I suspect they don't. I'm fairly sure they don't include the ability to photograph or record numbers of speeding drivers (because it wouldn't be sound as evidence to prosecute); but I could be wrong about that.

I will try asking the Council highways guys for their borough-wide strategy for deciding where to put these, and whether/how they monitor the effectiveness of each deployment.

I'll also suggest putting one, at least for a time, on Perry Vale outside the station entrance.