ANt wrote in message ...
The existing kitchen (a 70's flat roof extension looking from the
outside) was dry lined so the plan was to gut the kitchen back to the
brick, plaster and fit the kitchen etc etc. (there was damp and I
needed to get a chemical DPC in so needed gutting anyway)

Can't believe a 30 year old structure would be suffering from rising damp.

First day on the job and I get home tonight to find behind the dry
lining the wall was painted..looks older on the inside than the
outside also..hmmmm...I guess that's why they dry lined :-( The paint
is very flakey and the old brickwork quite crumbly.

Oil paint on the inside is a sure sign that the previous owners had
penetrating damp problems, and flaking paint is pretty conclusive.

Now I have until next Tuesday to remove the flakey paint so that the
plasterer has something to key into.

I think I'd postpone the plastering. If the DPC doesn't solve the whole
problem (which I'd put money on), you'll be back to square one.
As someone else has said, why not plasterboard it again and just get the
plasterer in to skim it? Try one board and see if it stays dry. Has to be
easier than needle guns etc (though of course less work for the
plasterer.....)
I would look at the outside pointing. If it comes away cleanly from the
brick, it's not doing its job and should be replaced.
Then of course there's the flat roof. They always leak but you should see
evidence of that on the ceiling as well.
I think you need to find the source of damp before thinking about plaster.