Agreed, the path nearest the note is not in the PROW map. But the next nearest path (mapped as Indigo Walk) would seem to be FP 21-22. It's not currently identified as PROW on OSM so I suspect the marker should be pointing to that. It may be that the original poster did not zoom in far enough to position it accurately. Anyway, the haringey map is showing Indigo Walk as a right of way, so I've added appropriate tags to that. 

