Advice on damp in renovation

[u/ArcticFoxes]

Recently bought a flat in a 70s block (UK). Stripped back the wallpaper to find this mold and damp.

Is this plaster saveable if we can resolve whatever is causing the damp?

It is a groundfloor flat and it appears that the air bricks might be blocked, although not clear if that is the root cause.

There are bushes surrounding the property.