@FTLApls please call TFL on 0343 222 3333 first thing on Monday and ask for the video, they will put a DVD in the post and put the penalty on hold while you wait.
In any case you have a bomb-proof appeal as the PCN purports to have been posted on a Sunday, the regulations say the PCN must be dated the day that it was posted, and I have an FOI response from TFL confirming they only post penalties Monday to Friday, so that's an open and shut procedural impropriety.
But let's get the video first as we may be able to find additional grounds.