Winfield House is a mansion set in 12 acres (49,000 m²) of grounds in Regent's Park, London, the largest private garden in or close to central London after that of Buckingham Palace. It is the official residence of the United States Ambassador to the Court of St. James's.
U.S. President Barack Obama and First Lady Michelle Obama stayed at Winfield House during their visit to London on March 31-April 2, 2009.