Beware new speed cameras
Actually probably old news by now but some may still not be aware.
The government has begun rolling out new "stealth" speed cameras across the UK. Current locations include the M1 in Derbyshire, M6 in Staffordshire, M25 in Surrey, M20 in Kent, M25 in Kent, M62 in West Yorkshire and M4/M5 in Somerset.
Thousands of motorists have already been caught by these new "HADEC" cameras.
What to look for
The cameras are mounted on the SIDE of gantries, i.e. not across the top like you would usually expect.
The FIRST sign one is coming is a grey pole in advance of the gantry on which are 3 cameras thus:
These ARE NOT the actual speed cameras. These cameras are monitoring the gantry signs to detect if they light up and display variable speed limits and if so they inform the real cameras on the side of the gantry what that new speed limit is.
The ACTUAL speed cameras look like this:
This is a sophisticated laser camera that can cover all 5 lanes of a motorway at the same time and which will also take photographs of your number plate, then automatically send the pictures and data to central control which will issue a fine and also create/log a court file.
In practice the police have stated that they allow approx. 10% + 2mph above the limit before issuing a ticket. So on a standard 70mph motorway that means after 79mph. Most people are unaware that most car speedometers actually display your speed at 2-3mph above the actual speed. So if your speedometer says you are doing 53mph you are most likely only doing 50mph in reality. That is why, when you are in those long stretches of 50mph road works and you are keeping your car just under 50mph, you see other cars seemingly whizzing by. You are actually only doing about 46mph whereas those other cars know that 53mph on their speedo is 50mph and that the police would only issue a ticket at approx. that plus 10%+2mph. i.e. You would get a ticket at 57mph which means your speedo would have to be showing approx. 60mph.
In the end the best policy is to keep within the speed limits but occasionally we aren't monitoring our speed every second, and are dutifully watching the road and other road users instead. So when on the motorway, look out for those grey poles with 3 cameras mounted on them just before a gantry and when you see one, check your speed.