Leaky Windows

I think I blogged last winter that some of the Bradstone window surrounds let water through. We have been very bad and just ignored this problem, hoping, I suppose, that it would go away as the building dried out. Of course, this hasn't happened. The first sign of wet and wintry weather and this problem has reared it's head again :

I spoke to the builder and asked if he and a representative from Bradstone could arrange to meet here on a wet and windy day to see this problem for themselves. His first thought was that it was the joints letting water through, but as you can see from the pictures, this is not the case.