Even though a summons has been issued, it might still be possible to pay the 60 pounds.
Write a nice letter and apologise for the delay in payment - make a good excuse if you possibly can - it's a bit 50/50, but they might still accept the 60 pounds.
Even if they don't, when you're in court waving the letter might earn you a certain amount of sympathy from the magistrates who might be persuaded to just fine you the 60 pounds.
Don't forget you're dealing with a "clearing system" and the system's objective is to resolve each case with minimum effort and expenditure.
On the other hand, if you fancy a fight, see these pages:
http://www.safespeed.org.uk/unite.html
http://www.safespeed.org.uk/pr111.html
Good luck.