You haven't really given me enough context to help. With that said, having looked on Google Maps at the pub you've mentioned, it appears (from what I can see) that there's a 3-hour max. stay and you need to register your vehicle as having parked to prove you were a patron of the pub because it's customer-only parking. There's probably a sign-in iPad or the like inside the pub to confirm you've parked outside and prevent being ticketed. If you didn't use the machine to enter your reg and evidence that you were a customer then that's likely why you were issued a ticket.