So today, 3 months to the day after my ill-fated 10k, I was finally able to go for a run with enough confidence that my thigh/groin would be able to take it.
And I'm glad to say that the leg took it well and, this evening, I am able to move with no problems. Phew!
I must say I was a little worried, who wouldn't be, but I took it nice and easy and didn't go very far. I jogged at a gentle half-pace to the running track up the river (passing the preparations for tomorrow's Arakawa Marathon, which I will join next year rather than Tokyo as it starts about 500m from our apartment), did a lap of the running track at half-pace and then jogged back home, stopping to stretch at various points along the way.
Probably about 3k in total but I didn't time myself as that wasn't really the point. We'll see how it feels tomorrow, but if tonight is anything to go by I should be OK. Now I can get back into it again - I have really missed running - but it will be slow, steady and short for a while longer yet.