Just as an additional thing, I bought a Brennenstuhl moisture meter to see if the wall was definitely dry. I'm disappointed to find that the area where the paint lifted is showing a reading of 19-20% (borderline medium-high) and it reduces to 10% the further away I go. In the small areas where I haven't removed the coat of Dulux Diamond Matt I get a reading of 0 which suggests to me that the paint forms some kind of moisture barrier. Is it likely that removing the paint from the blistered area will allow it to dry out further or is ongoing damp likely to still exist? There haven't been any crystals since I got the paint off a week ago and it looks and feels dry but I'm reluctant to put the ARP on if there's a still a chance of damp. Thanks.