They say things get worse before they can get better, and that is certainly the case here!  Building work has begun with a vengeance, and it is NOT a tidy process!  The rest of the ceiling has come down, along with the fireplace wall.  The ceiling is made of Lath and plaster (and not latham plaster as I previously thought!).

A quick google gave me this description: Lath and plaster was a method of finishing off walls and ceilings used from early in the 18th century right up until the mid-20th century.  The laths are thin strips of timber which would be nailed to vertical timber joists or posts to form a framework for the wall. Each lath was spaced with gap of around 6mm to take the plaster which would be applied next.