The LR belongs to an old pal. He's just filled me in on the details.
Apparently the T5 owner got out with engine running relying on handbrake only. The whole lot went backwards until the boat buoyancy floated the trailer and lifted the back of the T5 up on a jaunty angle.
By the time that Groomie was called with the 110, the tide had gone over the van. He reckons that if he'd been called earlier, he could've saved the van.