Is a parking ticket valid if the signs aren't easily visible?

I recently received a parking charge for overstaying at the Heathrow Sainsburys Esso service station. The ticket says the limit is 20 minutes and the signs, which I have now checked, say 45 minutes. The ticket says I was there 52 minutes. Does the fact that the authorised time stated on the ticket is wrong mean it is invalid? The Service Station has food outlets with seating for eating so inviting customers to stay and the signs are not easily visible.

Asked on 19 June 2017 by victor

Answered by Honest John
Every filling station, service area, drive-in and hotel in the Heathrow area has parking restrictions to stop taxi drivers parking there waiting for fares. Since you admit you parked there for 52 minutes, which is seven minutes longer than the 24 minutes allowed, the Supreme Court ruling in Beavis v Parking Eye November 2015 gives the parking enforcer the right to impose this penalty on you.
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