If you want to challenge the allegation you will have to decline the fixed penalty offer and plead not guilty in court.
There you will have to cast doubt on the reliability of the equipment used to measure your speed. The police will produce evidence to show it was measured by an approved device operated correctly. Do you feel able to do that?
The cost of failure is high. You will pay a fine of half a week’s net income, a surcharge of 40% of that fine and prosecution costs of around £650. No change out of £1k for most people.
You my find that the choice has already been made for you as your fixed penalty offer expired last Tuesday.
