If you were legally parked, you will be fine. Quids is right, these guys try it on all the time. As we all know, they're on commission, so it's not surprising that they hand out tickets even when they're not certain it's legitimate. Don't pay the fine, follow the "representation" procedure. Write a letter, including any evidence you have. If the council are stubborn, they will reject your first representation. If this happens, take it all the way to the personal hearing - chances are that the council will give up at this stage and you will automatically win. Keep at it... it's a very long process, and don't be put off by their attempts to raise the fine over time.