No, it's too late. Just going to have to plead guilty, as you said limit is a limit.

Thank you both! Lesson well and truly learnt.

Thanks for your reply sgtbush. Could you clarify for me that the law is that you must travel at the temporary restricted speed (in this case 50mph) until you see a sign with the national speed limit of 70 mph? In this case the speed restriction took place within 6.2 miles, there was no signage upon the exit to say that the temporary speed limit was lifted. I travel along this particular route fairly often and was able to check the next time I drove along this stretch of motorway. I mentioned going at the speed of the other drivers only because I was once pulled over for driving too slowly and the PC told me that I should maintain the speed of the other drivers in order to be safe. I have used this as a rule of thumb ever since, but I take your point.

I received an NIP for "speeding" on the motorway in a speed restricted area. The signage was very unclear and when I sped up it was because I thought the speed restricted zone had ended as there was no signage to suggest otherwise and other motorists sped up too making it unsafe for me to continue at the restricted speed. I was recorded as going 9 miles over the speed limit when I called to ask about this they told me that it was an average taken from when I entered the zone and when I left. Does anybody know anything about how they work this out? And how I could challenge this? The Police have sent me photographic evidence of my car but the photos do not show the context and thus you can't see that there were no signs around telling drivers to maintain the restricted speed. Is there a requirement to provide photographic evidence of the context? Can I do a freedom of information request? Many thanks!