Free Traffic Legal Advice

Just seen an invoice from them for stopping for ONE minute at Frimley Park Hospital Surrey on the road out.  there is a possibility that yellow lines are in existence... but do they carry any weight legally on  Hospital property?  which i assume it as otherwise it would be local council authority.I sm going there on Friday  to check it out  re signs etc   The driver is a bit agrieved as the time shows stopped for   0hrs 1min 0 secs!!  and stopped as a warning sign popped up re seatbelt. checked everything ok  and carried on.Are UKPC litigous? and for 1min is it worth going to popla?

Have more info  on situation
with copy of the invoice

What info, other than name/invoice number   pics etc  need to be redacted?
Also have diagram that may help

Ok Link read
Haver visited PALS this am and they said i was to appeal and once givern a PCN number? ( surely this is the  parking charge reference number?) to contact the Frimley Hospital appeals site
I looked at the UKPC site and it would appear that i appeal to them first and have a choice of three options  Driver/Registered Keeper/and Driver AND registered keeper,  i have not completed the form ,but would my first contact be a registered keeper
I have also drafted a letter to the Frimley appeals asking the.as employers of UKPC to waive the charge as it was no longer that one minute and the reason for not proceeding was a safety concern that was rectified in the time claimed. perhaps using 'de minimus' as a reason.
Therefore would my next action be to contact Frimley first and see their reply ,or go to UKPC site who no doubt will reject it?   Just need to get everything in correct order
Thanks