I don't park on double yellow lines, wherever they are, therefore I wouldn't have volunteered for a ticket in Teignmouth. May I add that your headline about two-thirds of parking tickets being illegal, is not just misleading but is in fact a downright lie.
Parking fines are voluntary. I've never had one in 35 years of motoring because I can read signs, see yellow lines and have enough intelligence to follow simple rules. If you volunteer for a parking fine, pay up and shut up. Any whining sounds childish.