Lobster wrote in message
I've just been investigating my newly emulsioned paintwork further;
there's little doubt that if you scratch at it, the paint readily
peels off the plaster. Omigod. I've already done several rooms
completely; looks fab, but clearly won't for long.

I've had problems with Dulux emulsion. Crown is "thinner" but seems to cover
and adhere better

What are the panel's suggestions for the few remaining rooms, in which
the newly skimmed walls have already been treated with 4:1 PVA? Is
there a way I can undo its deleterious effect before painting?
Sanding off a few microns and then doing it again with dilute
emulsion? Yeeuch.

IME a coat of 4:1 water/pva doesn't create a film over new plaster but
subsequent coats may well do. In this case the first coat of paint should be
applied sparingly so that it looks more like a wash. Once the initial bond
is there the 2nd coat normally takes well.