JB wrote:

I disagree that paying necessarily undermines the OP case. I was
advised by my solicitor to pay a charge I didn't think was
appropriate on the basis that otherwise the CPS would have a "lean"
against my car. She told me to simply write an accompanying letter
saying why I didn't agree with the penalty and why I was still
paying.

'lien' rather than 'lean'...

Thank you. :-)

I had visions of you returning to your car one day to find a CPS lawyer
leaning against it to prevent you opening the door :-))