In reply to John Beeston:
I have a mountain 25, the groundsheet started letting in water about a year after I bought it. NF put in a new one without any problems. But on my last trip it was letting in again - a wet sleeping bag where it hung off my thermarest, not nice. I expect
NF will sort it out again, but that's not the point. If it hadn't been a good day to dry my gear I would have had an unpleasant following night. This is not my only tent; I have 2 Terra Novas that haven't ever given me any problems. Personally I would not buy another NF tent, but perhaps I've just been unlucky - will be interested in what other people have to say.