In 1979, excavation within part of the former library at Audley End House, Essex, brought to light debris from the plaster ceiling erected between 1753 and 1762, and much workshop debris relating to the decorative plasterwork executed throughout the new Great Apartments by Joseph Rose, Sr. to the designs of Robert Adam in 1764-1766. The latter material is used to demonstrate in detail the technology of decorative gypsum plasterwork. This is contrasted with the methods used by the stuccoist Thomas Clayton at Chatelherault, Hamilton, Lanarkshire, c. 1742-1746, and the eclectic technology evidenced in the earlier library ceiling at Audley End. Finally, the development of the technology of decorative plasterwork in Britain between the 16th and 18th centuries is reviewed in light of information currently available.