The first house on the site was Hertford Villa, the largest of the eight villas originally constructed in the park, in the development scheme of John Nash. This house was designed by Decimus Burton in 1825 for Francis Seymour-Conway, 3rd Marquess of Hertford, who used it for orgies. Burton's creation was described as, 'decorated simplicity, such as the hand of taste, aided by the purse of wealth can alone execute'. Burton's creation was subsequently reconstructed as a building with a modern exterior. Later, the Georgian villa was known as St Dunstan's because of the distinctive clock that hung in front of it, which was purchased by the art-collecting Marquess of Hertford when material from St Dunstan-in-the-West was auctioned off in 1829–30 prior to the church's demolition for a road-widening scheme. Subsequent occupants of Hertford Villa included American financier Otto Kahn and British newspaper proprietorLord Rothermere. During the First World War, Kahn lent the house to a new charity for blinded servicemen, which took the name of St Dunstan's. After a fire in 1936, the house was purchased by Barbara Hutton and then demolished.
Winfield House
Hutton commissioned a new mansion to be built in the Neo-Georgian style, which was designed by Leonard Rome Guthrie of the English architectural practice Wimperis, Simpson and Guthrie. The house was at first known by the name of its predecessor, but Lord Fraser of Lonsdale, head of the charity, approached Hutton to explain that the similarity in the name and location of her house and his organisation caused confusion, and he asked that she give up the historical name. She agreed to the request and chose a new name, derived from her grandfather Frank Winfield Woolworth, who had an estate, Winfield Hall, in Glen Cove, New York. During the Second World War, the house was used by a Royal Air Forcebarrage balloon unit and as an officer's club. It was visited during the war by film actorCary Grant, who was married to Hutton at the time. After the war, Hutton sold the house to the American government for one dollar. After extensive alterations, Winfield House became the ambassador's official residence in 1955. The previous residence at 14 Prince's Gate had been deemed inadequately secure. The house is listed on the U.S. Secretary of State's Register of Culturally Significant Property, which denotes properties owned by the U.S. State Department with particular cultural or historical significance. The interiors have undergone extensive alterations at several points, including in 1969 by William Haines, a decorator and former silent film star.
Grounds
Winfield House is situated within twelve acres of grounds set into Regent's Park, which includes a small front wood, sculpture garden, formal garden, vegetable garden, and tennis court, as well as an extensive lawn which comprises the majority of the acreage. Pathways and drives extend into the grounds, and connect the front garden and entrance to the rear. The property is surrounded by trees, primarily for security and privacy.