I'd just introduced myself to Mo - who was over a hundred miles away - when she said, suddenly, 'There's a man on your roof.' I went to investigate and there was indeed a builder, who was working on our house at the time, on the roof. 'Tell him to mind out for the flashing,' said Mo, when I returned to the phone. She's a former surveyor, a practical type; but I don't even know what flashing is, and despite my surprise about her rooftop vision, I thought no more of it.