OP, the marking is nonsense.
It is not lawful to place the 'wheelchair' symbol on the public highway, therefore, despite there not being any signs to this effect, the land is private. The fact that Southwark paint parking bays on their land is their business, but it doesn't give rise to parking contraventions enforceable under the Traffic Management Act, which is what's happening here.
So-called 'traffic' signs(a term defined in law) are irrelevant because they only apply on-street, unless the landowner has erected clear notice(s) to the effect that this is private land (quoting the relevant order and landowner) and that such and such conditions apply, bays reserved for specific use are marked as follows and failure to comply with any restriction or requirement may lead to....
So, where is this sign(s)?
