Defused

The driver behind the action to sort out the surplus pipework was this patch of corrosion - a sprinkler waiting to happen.

Working with the plumber we think we know where this pipe comes from, and we know it goes nowhere, so the task is to drain it so we can remove it (which, blip-evidently, we have succeeded in doing).  Also removed several metres of redundant central heating so the original four pipes is now one.