Work on the construction of Frogmore House began in 1680 and was finished in 1684. The estate itself (within the extensive grounds of Windsor Castle and Park) was owned by royalty for about 100 years before the house was built. The first resident was George FitzRoy, 1st Duke of Northumberland. He was the illegitimate son of Charles II and Barbara Palmer, 1st Duchess of Cleveland. In 1792, George III purchased the house for his wife, Queen Charlotte.
Queen Charlotte needed an escape from the demands and rigours of Court life and so she and her unmarried daughters would retire to Frogmore to pursue more ladylike pursuits.
The house was modernised by James Watt between 1795 and 1804. Most rooms were altered and the building was extended, especially on the second floor.
The Duchess of Kent was granted tenancy in 1840, and that led to further alterations, especially with regard to internal decorations. From 1925 until 1953, Queen Mary used Frogmore as a kind of museum, gathering together all the royal heirlooms and souvenirs. When the Royal Yacht Britannia was decommissioned in 1997, the Duke of Edinburgh moved most of its contents to Frogmore. When it was realised that Britannia was now stark, some were moved back, but Philip remarked that Britannia had been a great venue for the promotion of overseas trade, and equipped part of Frogmore to be used likewise.
There were further renovations during the 1980s, particularly with regard to what Queen Charlotte had wrought. The house is no longer occupied, but is frequently used for Royal functions and entertaining.