Called in these guys to find a leak coming from a mid-floor ceiling in a sizeable former pub which could have emanated from a pipe pretty much anywhere between the ceiling and the floor above. They turned up swiftly, got straight to work and succeeded in finding the problem with the minimum of disturbance to the building in terms of pulling up floorboards looking for the source of the leak. Took two hours (I was paying an hourly rate) and would have taken a lot longer if not for a good assessment of the the most likely place the leak might be starting from.
