If speed cameras are a stealth tax then I wish all stealth taxes were the same, then I wouldn't pay any.
Speeding is an issue that cars have had almost since the point that flag carriers in front were removed, but for some reason it has never been socially unacceptable, even with the efforts of campaigns like 'Think!'. The issue with speeding though should not, IMHO be a case of increasing the punishments or lowering speed limits per say, but rather that of enforcing the limits that are already there. I would suggest that the following would make a greater impression on speeding than draconian punishments that would make more law abiding drivers feel under siege and may encourage more people to see the limit as the target and not think abaout driving at a safe speed for the conditions.
Speed cameras
With respect to speed cameras, I would suggest two 'improvements'. Firstly on roads with limited entry/exit points (like motorways) it should be simple enough to install ave. speed cameras at each junction. This would mean that the whole motorway system could be kept at speed limits, and would have the added benefit of allowing variable speed limits to be introduced like those on the M42. Secondly why not camourflage the speed cameras instead of painting them bright yellow. This would make it far harder to 'camera surf'.
Speed limits
I would favour the lowering of 30mph limits to 20mph in post urban areas rather than lowering 60mph to 50mph roads. Firstly there are far more non-motorist users of urban roads than rural roads and also from a purely personal motive lowering speed limits on trunk roads in areas like Cumbria where motorways don't exist would leave us even more cut off than we already are.
What may be an intereting trick would be to switch from mph to km/h, as from trips to the continent I feel psycologically it feels like you are going faster at the same actual speed.
Others
I would be perfectly happy with changing a speeding offence to 4 points from 3, and removing the "I need a car for my job" defence at court for those who hit 12 points. Would it also be sensible to have a scale of points and fines depending on where and when a speeding offence occured, as it is more dangerous to speed at some times and in some places than others (though all speeding and is just as wrong)
Also enforcing a defensive driving course to be taught to all drivers, including those who already hold licenses, and introducing more shared space areas to remove the defining and percieved ownership of certain areas of the road would both be benifical IMHO.