Took a trip up to storage today to put something temporary in place in the hope that the wet section of the floor may dry out a bit.
Fistly I liberally coated the wet areas with Black Waxoyl ( thank you David Mantell for that suggestion ),that was a messy job.
Secondly I taped some plastic sheet across the rear of the van in order to prevent ( or certainly reduce ) water running underneath and secured it with Gorilla tape.
Having had a close up look underneath I think the problem is in the centre section of the van.
The end section bodywork doesn't actually touch the floor so I don't think the problem is there.
The centre section bodywork however is not attached to the floor but to a piece of wood that fills the gap between the bodywork and floor giving something to screw the bodywork to.
This piece of wood was very wet,presumably from rainwater clinging to the bodywork and wetting it as it was very wet indeed.
I think this wood gets wet and the excess water runs off to the corners where it can go no further and soaks the floor.
There were some gaps in the corner trim which I filled with Waxoyl but whether these contribute to the problem I don't know.
My long term plan is to get a piece of L shaped aluminium and secure it under the back of the van in the centre section to act as a 'drip strip' so the bit of wood doesn't get wet.
Needed to get something in place as there was a possibility we would get locked down again but we seem to have escaped.
Secondly I had an e-mail from John who suggested that the problem may lie with the cassette locker door seal letting in water in driving rain,he has had the same wet floor problem,changed the seal and all was well.
I have heard similar things on forums as well
Having checked it I couldn't see a problem and was going to leave it at that but as the seal is only about £20 or so I will swap it anyway for peace of mind,thanks John.
Will leave if for a few weeks and see if the floor dries a bit.
Will keep the blog posted on events.
Ian