Check the plastic sheet behind the interior door panel for gaps.
The plastic is intact, adhering all the way round. The door rubbers were cleaned and fed with autoglym rubber treatment. The air-con needs a re-gas but the matrix doesn't appear to be leaking - no coolant loss at all. There's no corrosion (yet) under the car or in the footwell.
The bulkhead drains appear to be clear ( I was in teh process of trying to clean them when I ***cked my windscreen.The bottom of the windscreen and rear window have a poor seal though. Heck, in truying to solve one problem I've just caused anothr... still a new screen should rule out the suspect seal :/