The photo on the PCN does not show you passing a sign for your direction, only ones for the opposite direction, so submit reps on this point. However wait for others to comment because there may be a 'technical' appeal argument totally unrelated to the alleged contravention. These technical appeals are based on council mismanagement of the enforcement process and often win at London Tribunals. Be aware that whatever you submit, no matter how valid, the council will reject them, because they know that if they do, >95% of people then fold and cough-up. If you are to fight PCNs like this, (assuming your case looks OK), you must be prepared to stand your ground and ignore the attraction of the discount.