My Pastiche had water on the front ledge 4 weeks after we bought it new - turned out to be capillary action from wrongly installed front window seals. Rapidly fixed by Coachman at the factory (away 2 weeks) and hasn't recurred. Initial fear was panoramic window, though.
More recently, streaming water from the off-side top front locker. My Dealer rang Coachman and a temp fix done that involved sealing the 'pod' that covers the end of the roof bar - no recurrence to date and the 'van has gone off to Coachman for repair, again. But see below. Have picked up from other Coachman owner somewhere on a touring site this year that this problem is by no means unique - in fact it seemed a bit suspicious to me that Coachman could provide a fix by return, over the 'phone, at a week-end!
Most recently, I've had free water appear in the bathroom after towing in appalling weather - I'm thinking those pods again.
But I'm sure that Coachman will get it sorted.
I'll keep this thread posted on developments.