Thanks for the replies, which are both appreciated. I tried responding on my phone last night, but the screen was too small to see what I’d written. I’ve dried out the small area of internal wall effected, no problem, and have sealed the outside temporary with tape over the rubber gasket seal, which has worked well . I intend sorting the issue next week and will update this thread with my approach as there’s bound to be others who just need to understand the issue a bit more before starting work.
Good new is that the rest of the van is 100%.
Many thanks all
Keith