In reply to hokkyokusei:
> Not sure. By the time I saw her, the indicator would probably have been obscured.
Fair enough. I would say on your part, that hazard awareness might come into it, but it's hard to say, not having seen the road in question. Also if there was a line of traffic, then you might have found it impossible to see over the cars I guess? Maybe worth upgrading the brakes on your bike so you can stop quicker?
On her part, the Highway Code is quite explicit about flashing head lights:
"110 - Flashing headlights. Only flash your headlights to let other road users know that you are there. Do not flash your headlights to convey any other message or intimidate other road users.
111 - Never assume that flashing headlights is a signal inviting you to proceed. Use your own judgement and proceed carefully."
So she should have had a good look and not just gone and the excuse, we'll I'd been flashed so it was ok to go is total oblocks.