Edgcumbe House was built in 1740 as the town house of the Edgcumbe family of Mount Edgcumbe near Plymouth.

The building is of Cornish granite and is well proportioned. The two upper floors are let as offices and the ground floor contains the Town Clerk's office and the Mayor's Parlour.

The Mayor's Parlour has a beautiful plaster ceiling and panelled walls with a marble fireplace and contains ceremonial and other items of interest. The table is Jacobean and the large cupboard dates back to 1667. The chest with three locks is thought to have been the Town Treasury with all three keyholders required to be present when it was opened. The chest inscribed 'Borough of Lostwithiel' contains the standard weights and measures dated 1741 which were used by the Town Council to police as the local Weights and Measures Authority.

The Mayor's Parlour