I'm going to bullet point a few things here as I've been through this matter at a different location.
1. It doesn't necessarily matter whether driver did or didn't manoeuvre car as alleged by PCN / council. The PCN is citing legislation and that the driver has contravened this but that also means the PCN has to abide by certain legislation governing what is required on it and that signage including road markings also complies with the necessary legislation for the contravention to be valid / enforceable, otherwise it's basically a bogus claim asserted by the council.
2. What matters is whether the PCN is legally enforceable and that means it must be worded correctly, the signage must be in accordance to correct legislation, traffic order doc etc.
3. Is there proof that a contravention occurred regardless of whether it did or not. Sometimes if there is no video footage of the vehicle and sign together then where is the proof the sign was there at the time? If the signage is incorrect then technically the contravention can't have occurred as all the requirements have to be in place otherwise it doesn't represent the legislation governing the use of said signage, traffic orders etc.
4. Unfortunately we have a system with these that pressurises the motorist to pay up or prove their innocence and the council's use this to their advantage by issuing charge notices on mass even when they know they're not enforceable due to previous appeals being upheld. The system in the first place ought to be criminal imho.
5. The burden of proving your case is going to cost you more than the ticket so only those who can afford the time are likely to pursue justice against this practice. There are no guarantees your appeal will be upheld even if you find deficiencies in the PCN or signage as the appeals process has been shown to be inconstant even with the same circumstances and adjudicator. I didn't already say the whole thing is a big pile of steaming poo but it really is.
The best place to start if you feel genuinely aggrieved or feel a sense of duty that others also shouldn't be fleeced in this way is to follow the post on this other forum regarding posting up images of your PCN, recent pics of the location. There's some great knowledgeable people over there that dedicate a lot of their time to pointing people to the right bits of legislation so you can cite these in appeal documentation that you will need to draft.
http://forums.pepipoo.com/index.php?showforum=2
I won my case against Coventry City Council with the help of these folk but it took a lot of time pulling all the info together. I only wish it had meant all the other thousands of PCN's unlawfully issued had required them all to be refunded.