On 14/05/2020 13:54, newshound wrote:

Old property? Potentially damp wall? Has the plaster been sprayed with
silicone? Does it have to look "good"? If not maybe undercoat with SBA??

It's an old property but was refurbed a few years ago, beyond that I
don't know. There's no damp.

It doesn't have to look amazing but needs to not look a bag of..... but
i'm not spending 10 quid per litre on acrylic based paint!

I'll get as much off as I can scrape off and attack it with PVA* before
painting, or would lining paper be better?

* Suggested by a decorator in the family, but I thought that was a no-no?