I've got a problem with a room which has very old plaster walls, 3 of
the walls are brick with plaster, which I'm not too worried about,
I've patched some holes and the whole lot feels pretty strong.

The forth wall however is just wooden slates with plaster, and no
mater what I do with it, it just feels weak.. (If I push the middle
of the wall it bows a bit)

I'm thinking I could fix plaster board to the wall to give it a bit of
strength (not sure just how much strength it would give it?), is this
a good idea? If so, how do I fix plaster board to a weak wall?

Any ideas???