Ah mate, that's a bastard. I would have argued the toss especially if the speed limit signs are so close to the cameras. Might be worth getting photos, measurements and anything else that you can submit as mitigation. Play heavily on your excellent driving record and appeal to the courts sense of fairness. Why the hell that couldn't just issue a fine beats me. Get a free half hour at a local solicitors and get their view. Apart from that I sympathise with you. This country sucks now, the government is just out to stitch us all up. Best of luck mate, keep us posted.