Have you viewed the video ? The video starts with the car already in motion, so it doesn't show the distance of the reverse movement. However, as this is a one-way street and obviously known as such by your uncle, it will be difficult to escape this PCN. He was unlucky to be close to the camera for the Flying Motorbike signs as I suspect doing this anywhere else on this street would be unobserved. This is money-making game, I'm afraid and councils ruthlessly enforce the slightest contravention because it makes them so much money.
There may be an alternative appeal option based on Newham mismanagement of the enforcement process. The expert on these is Hippocrates, so hopefully he'll post here soon to tell you if there is one. The downside of such appeals is one must take the council to London Tribunals and risk the full PCN penalty, (or nil to pay if you win, of course).
