Alan you are better off just pay it mate you know what they are like!
I've been in the same situation my ticket flew off the dash hit the floor when I shut the car door!
They had pictures of tax disc, reg and car dash everything to prove I didn't have a ticket on the dash!
I sent them the ticket to prove it and they just sent me there thick photo copy of the fine print saying unless a valid ticket is shown this is a chargable offense the fo*ckers waited until the ticket would go into the extra fine mode 10 days after so I had no choice to pay the dam thing!
Trust me better people have taken them on and lost!
Just want you to swallow it fella before they make you pay more!