Intermittent broadband fault, when Plusnet sent the *second* POTS engineer I was wondering how long this would drag on for.
But all credit to the man, although there was no phone or broadband fault showing he decided to look at the drop from the gutter (made easier by the fact that I already had a scaffold tower up there). Hooked up to the connectors, pulled the supply wire and the line drops out. Ladder up the pole, new supply wire and all fixed in about 20 minutes. The only pity was that he disappeared without giving me a chance to say thanks.