Speed cameras: the myths exposed - You can drive about 10% over the limit

'Police forces allow for speedometer error of 10% plus 2mph, which means 34mph in a 30mph zone is acceptable.'

No.

The Association of Chief Police Officers has a minimum threshold for enforcement of 'Speed Limit + 10% + 2mph' which is 35mph in a 30 zone.

If you are willing to gamble your licence on the accuracy of your speedometer, you could 'get away' with 34mph - but you shouldn't be speeding anyway.