We've seen this location before, last year, I think.
I had a look at the appeals at London Tribunals and all were refused bar one which centred on the appellant being the hirer of a vehicle and the hire agreement did not allow transfer of liability to him. All the others centre on the actual NRT sign, although none seem to point out that the text below the sign cannot be read until the driver is committed to the turn, there being no advance warning sign. So this argument could be submitted in representations, but, needless to say, with the full PCN penalty in play.