Physio visit involved a recap of the MRI results (mild ITB irritation, fat pad inflammation and mild fraying of the cartilege - perhaps related to the syringing many years ago) and a bit of a trot with physio in tow, assessing my gait. Apparently my back is very rigid, my hips do something weird and one foot does a floppy thing every 5-6 steps at slow speed but at fast speed my gait becomes much better. He prodded my hips and glutes and did some deep-tissue work on those (OW!) to loosen things up a bit.
Current thinking is to tape my patella to encourage it to move a bit differently, to see what effect that has on the pain:-
Will go for a decent run at the weekend to see how that works out. And in the mean time physio is drawing some pictures and having a think about what's going on with my hip movement to see what's going on there. With 1 week left to London thereafter there may be some other interim management required to get me through that before the more long-term management strategy.