Of course, having arrived, he took one look and said "That's too damp for me to work on."
I actually phoned the builders 10 days ago to ask what was happening about dehumidifiers. And they delivered one last Friday, having popped round first, and told me I didn't _really_ need one, but what the heck, they'd give me one anyway.
It didn't actually work though - it even has "Not Working" written on top in marker pen. So I phoned them back on Monday and told them.
Cue a complete lack of them delivering a working one.
So, it'll be sucking moisture out of the walls until Monday, and then hopefully the room will be ready to be actually fixed.
Chances of it actually being finished before I go away next Friday...slim.