One of the earliest and largest houses in Hampstead, Fenton House is one of the best architecturally. Similar in plan and elevations to medium-sized houses built by London masons like the Stanton family, it was built around 1686 by William Eades, the son of a master brick-layer. This may explain the accomplished brickwork and absence of carved stone.

The south front displays many of the building’s characteristics. The material used is a deep brownish brick, with rubbed red brick for the dressings, including the window frames and corner quoins. A plain string course runs between the two principal floors. The three centre bays project slightly and are surmounted by a pediment. The door case is also pedimented, on Doric pilasters. Under the eaves is a boldly carved wooden cornice typical of several in Hampstead that date from the early eighteenth century.

The ground plan of the house is a perfect square split into quarters by a cross; two arms contain the staircases, the others the hall and landings. Each of the four rooms on the two principal floors had closets, considered essential for bed chambers, many with small cupboards leading off them, where chamber pots would have been kept. Fenton House is unusual in that closets were built for the main rooms as well as the bed chambers.

It was the Fentons, Philip who bought the house in 1793 and his nephew James, who gave the house its present name. It was probably James who made the Regency alterations which give it its current appearance. He added the colonnade to the east front. Changes inside the house were confined to removing partition walls to enlarge rooms on the ground and first floors.