Owning your own home

Vapour is meant to pass from the inside to out but a repeated large build up of moisture on the inside of a building is unlikely to be solved by taking down gypsum plaster and replacing it with lime plaster.

Yes there are many problems with period properties, many of which are caused by poor maintenance choices over their lifespan. You have to remember that when your period Victorian house was built peoples homes worked in a very different way. If you live in a Victorian terrace it is likely that the building was designed as a series of basic rooms that were heated by an open fire that actively drew air out of a room and up the flue. Period windows aided this as they let air in, even when closed, as they weren't exactly draught proof. Modern uPVC windows are pretty much draught proof and many fire places have been closed off, often badly, even if the nice cast iron period fireplace is still there as a design statement nodding to a building's past it's likely that something has been shoved up the flue to seal it. This has a tendancy to hold water in the flue which can cause problems.

People's personal hygiene was also radically different and was very, very unlikely to involve a shower; a device that is very good and getting you clean quickly but also very good at raising the humidity of a whole house very quickly.

Added to all of this is the fact that many walls in these properties are solid construction so cold bridging is a constant issue allowing condensation to build up on them. Especially when central heating is doing a much better job of heating a house than burning solid fuels ever could.

TLDR: Yes using lime plaster may help with moisture / damp issues but there are many more pressing issues.

Oh, and with the spalling that was mentioned up thread. Yes the choice of mortar may be an issue but before looking at that I'd first consider:

1. Previous attempts at repointing, if the wrong pattern of pointing was used or it was done badly this will be the #1 cause of spalling.
   
2. In all likelihood the QC employed in the manufacture of Victorian bricks was a bit hit and miss. Intact often houses were rendered to cover up and protect shitty bricks. Which brings on to...
   
3. If you live in one the only 2 houses in a street of Victorian terraces that isn't rendered it probably was at some point and someone stripped off removing a substantial layer of protection for the brickwork. This also has the effect of opening up flaws within the bricks accelerating the freeze/thaw cycle as water can penetrate easier.
   
   

Basically modern techniques and materials can be an issue. However it is possible to mitigate issues that may arise with forward planning. Insulating you back bedroom could well be a goer but if you are experiencing damp issues I'd identify and tackle the cause of that first, look at extraction in the bathroom and trickle vents in problem rooms. If it's actual rising damp there are steps that can be taken as well.