It doesn't mention that the internal plaster finish may be coal dust plaster (because Victorian and Wales), which is fucking terrible stuff, and worth being aware of if you have to strip the plaster to sort the damp.
Very common around here, virtually all the heritage mortar/plaster is black. It's a bitch to do anything that involves disturbing it (just mess, don't think it's particularly more unhealthy than gypsum dust) but largely unavoidable on anything Victorian.
It doesn't mention that the internal plaster finish may be coal dust plaster (because Victorian and Wales), which is fucking terrible stuff, and worth being aware of if you have to strip the plaster to sort the damp.