Thanx Tony,
I see you are an experienced poster here, but this was my first visit, so no idea about the history of the site.
So lets move on eh.
I understand the 'Tecko' was the guy who originally installed the boiler, but he may be good at installations, but not at diagnosing problems. I think he eliminated the pump, room stat, and disconnected a couple of printed circuit panels. I was there and re-setting the breaker for him each time his elimination process failed. But I did get the impression that he was struggling as he took the 'phone a friend' option almost as soon as he removed the front cover.
The house is in NW2,,, which area do you cover?