Hack Off Old Plaster Before Boarding and Dry Lining Over it?

[henrythedog]

We recently moved into an old two story, stone house which we're about to start renovating (room by room). First job is to plaster the bedrooms — plasterer has advised framing out the room, filing void with insulation on the two exterior walls and then board & plaster. My question is should I hack off existing plaster or just board over it? What are the pros/cons to hacking off the plaster back to the stone work?

Cheers

[lets have a look]

I can't see any benefit from hacking off the old plaster, personally I would buy plasterboard with a foam backing