I've looked really carefully for mites in the house - took the perches out and looked round the ends where I thought they might hide, no sign or them or their droppings. I also haven't seen any on any of the other birds. It is T&G and felt roofed so not ideal but suits in so many other ways - I'll just have to keep on top of the spraying.
Broody (and broody 2 now) seems much more comfortable and is well settled, eating well when she gets off and she's lost no weight over the last week, cleared her constipation (not lack of food, lack of being able to pass it - a dog would have been jealous) and is generally brighter so I'm now hopeful she'll make it through a further 3 weeks of sitting (she's done two weeks so far).
Do you know if I Frontline them all whether I have to discard the eggs for a while? Seems like a much easier solution than dusting - no hope of getting to all of their skin through the fluff.
H