Patrick, did sealing the hairline cracks stop the water ingress? I have sealed around the hinges, all cable inlets and around the rear cluster fixings etc. I too have these hairline cracks mostly on the drivers side around 1 inch inside the rubber seal flap (under the roof rail) they don't look large enough to allow this amount of water in but I'm running out of things to seal! The cracks look more like a hairline of rust when peering in from the end of the t-track. The water is coming through the vent on the c pillar and dripping onto the carpet above the small storage compartment on the side of the boot compartment. It's a shame as I've had 5 years trouble free motoring with this old barge..