'Oh, I'm waiting while the white light goes on,' she said.
Sure enough, by the trackside, there was a sign: Do not cross while white light is showing.
As an accredited non-directive counsellor, I could not, of course, tell her directly that her dialect use of the word while (by which she meant until, since she came from the Nottinghamshire/Lincolnshire border where that usage is common) was different from the meaning intended by the signwriter.
Instead, I asked her questions to help her clarify her options, and in particular her understanding of the word while. But as an autonomous individual, she made her own choice to stick with her understanding of while. And as she walked in front of the 3.15 to Paddington, I reflected on the ethical way in which I had handled the conversation.
Or to put it another way, there is a time and a place (arguably) for non-directive counselling, but when somebody's life is at stake due to ignorance (for example) that is neither the time nor the place.