The nice man from the NHBC came round on Friday to look at the roof. For most of the saga see here.
The good news is that he basically agreed with us (and the roofer we got in last week for an independent point of view) that the roof wasn't made in the best fashion. Something to do with the builders putting the drip trays for the cavity walls in the wrong place. They're meant to go above Molly's roof. Instead the builder seemed to think it would be spiffing to put it in Molly's attic. Water hits wall, Bricks absorb water. Water goes into cavity and onto drip trays. All as it is meant to be. But it's meant to come out of the damn wall and onto Molly's roof, washing away properly. But with the drip trays in Molly's attic all of the water has chance to leak into her attic. Morons.
The bad news is that the fix for this involves many days of NHBC builders on the roof putting in new drip trays for the cavity wall. This is complex and messy. Of course, it could be worse - the original builder could be doing it.
All in all, not that bad I suppose. A resolution seems to be on the cards, and it's got nothing to do with the original builder. Of course, me being me, I'll be looking at the attic, just to check, for the next few years every time it rains; just to make sure.