Hi Viking, Yes I have definatly arrived at the conclusion that ventilation is the best way to go. The moisture level meter is the type that is ment for timber and you poke the 2 probes into the material, Its not acurate but its useful just to get a referance point.
I thought the silicon cream may work as from what I understood it needed the moisture to actually migrate along and cure.
Yep will be doing the work myself , unless we win the lotto!
We are just going to leave the back wall plaster-less for the time being and see how it dries out, as the garage which is to the side of the staiwell and backs onto the wall has nothing on the bare stone and seems resonably dry.
Thanks again for the info.
Steve