So, I can confirm that all the S’s are serpentine and belonging to 9b with no star on breast. There is no perforation of the flan, and the rust on the reverse was not part of the coin, and has for the most part flicked off.
North did not identify any ANL errors for Class 9, though Wither’s, as Coys pointed out, has recorded a London 9a piece, but also a 9b1 (which this coin is) for York (but not London).
Therefore, to the best of my knowledge, this is an unrecorded obverse for London. Interestingly it arrived with a Spink ticket with 9b on it, but no mention of the legend error!
Only a phone image for now!