Three Fish, many thanks again… Got the tools out this evening, removed the battery and the battery tray, lo and behold there was a good pound or two of compost underneath the battery tray, much of which was blocking the drains!
So cleared the lot out, poked the drain holes clean, put it all back together etc… Also probably spent almost 2 hours in the car today, all of it with the heater on full blast (opened a window periodically to let some cool air in and the humid air out). Hopefully soon it’ll all be dried out carpets aren’t wet at least) inside, and I’ll probably get one of those chemical dehumidifiers to boost things a bit.
Anything to beat having to scrape the INSIDE of the windscreen again such as I had to this morning before leaving to go to work!!!