I have had such events twice. Once a parking violation in Northampton which was given as I was returning to the vehicle after having purchased the ticket in the machine. BTW, the alleged UK five minutes discretion for parking were not allowed to me. Further, I was visible to the parking warden as I was buying my ticket. Responded Northampton authorities; we don't care, you pay. Responded Hertz, you pay of we suspend renting privileges. I paid.

The other was in the US, in Charlotte, NC when I was ticketed for improper lane usage, using a Florida driving license. I paid the next day with a US Postal Money Order but the Mecklenburg county lost the record so suspended my driving license, which caused a Florida suspension also. I proved the payment but Mecklenburg refused to accept it. I then had to pay again, plus penalty and also pay Florida to remove the suspension. It cost me $250 plus the original $45 ticket. I did consult an attorney who told me it would cost $500 plus a court appearance in Charlotte to contest this, so I paid.

Moral: The authorities will get you if they wish and it is usually cheaper to submit than it is to fight.