Thanks for the advice (and magical healing powers I hope!). I have not noticed any regression in aerobic speed leading up to the injury or after. I've only done one LHR run since and it was in line with recent performance, actually a personal best for that particular route (average 9:25 MAF for 60 minutes on a pretty flat course).
Making the decision not to run even easier: I've come down with a nasty cold which is wiping me out. I guess someone else will have to get 38th place at the race on Saturday...
Oh, man, double-whammy.
Heal, heal, heal, heal, heal!!!!!!!! (thrusting of hands followed by speaking in tongues and a nice meal of bacon, eggs and fine cheeses)