In reply to BnB:
No, and that was why it was so noticeable. It's a lightweight jacket
http://www.ukclimbing.com/gear/review.php?id=2285 so it has been carried many places in packs but worn only when needed, but as best I can remember the time before I had worn it in the rain it had been absolutely fine, then the next time it leaked really quite obviously.
I know exactly what you mean by catastrophic, although that makes walking with the kids on a cliff top path a few miles from the cafes and ice cream shops of Robin Hood's Bay sound rather dramatic! Nevertheless it was taken and worn the year before that when we climbed the South Pillar of Stetind, and I clearly remember the conversation the day before as we packed, where we decided to both take full waterproofs but leave behind the bothy bag. If it had rained then and we had somehow become cragfast or similar, it could be quite a catastrophic way to find out your waterproof isn't!
BTW BnB, are you aiming to be up north all winter? Or might you be around for a rematch of doing a route in the Lakes at some point (if it ever actually gets cold and snows again down here)?