Well I had no idea that it was illegal to turn right there and I certainly did it in mid March and then again recently. It's hard enough to keep your eye on the traffic at that corner let alone being expected to pick up pointless no right turn signals.
If I get a ticket for turning right I will oppose it - the sign simply cannot be that obvious if I as a cautious and law abiding driver with over 35 years driving experience did not see it on two separate occasions in broad daylight.
Is this restriction a recent one or has it always been so? My experience has always been that the turn out of that car park, even going left towards Forest Hill is considerably more of a challenge than the turn in.