Unlike Income Tax, Fuel Duty and VAT this "tax" can be very easily avoided - by sticking to speed limits, or at least not exceeding them by more than 10%.

Given that most motorways are full of trucks doing 56mph, I don't see how enforcing the 70 limit will have any effect on congestion.

This seems an easy way for our cash strapped Government to make even more cash out of motorists.

there is a very simple way round this - don't break the limit and then you don't have to pay.

Also if you have ever seen an army of ants you will know they get about pretty quickly in all flowing along nicely. Are you saying you don't want to get about quickly and flow along nicely?

The fine would presumably be the usual £100 (and three points). Lets say for guesswork that half of that is swallowed by admin, maintenance of the cameras etc.

Now let's assume these cameras are set to usual 10%+1mph threshold, allowing for speedo under read you're going to be at an indicated 80+ to trigger them.

Two million fines ayear at a net return of £100m? A drop in the ocean of highways spending let alone overall tax take,