BT's link with GCHQ and the latter's monitoring of this site obviously did the business.
I got contacted by "off the page" Support early yesterday morning and had no less than two engineer visits yesterday where they found the problem and replaced cabling underneath the street outside. I now have full speed access and had a call by off the page's colleague tonight to check if all was OK and that I will contacted next week about compensation.
Someone asked why I am on BT. I took broadband when it first started up and my reasoning then that was better to deal with one lot rather than take another service that ran over BT wire and have to deal with the finger pointing. Why am I still on? Not many problems up to now, a btinternet email address that would be a PITA to give up and plain old inertia.