Thorncroft Manor

Thorncroft Manor is a Grade II* listed manor house, now used as offices, situated on the north side of Thorncroft Drive in Leatherhead. It was designed by Sir Robert Taylor in 1772 for Henry Crabb Boulton and has subsequently been enlarged and altered.

The main building is constructed of white painted render, probably applied over brick, with a flint plinth. It has a slate roof. The house is L-shaped in plan, comprising a rectangular double-depth main range on a north-south axis with an integral wing to the rear of the north end. It rises to two storeys over a high basement and presents a symmetrical five-bay façade to the east.

The basement is of slobbered flint with windows set in flint surrounds roughly keyed for a former rendered finish, though the glazing has been altered. The central entrance is reached by nine steps with rusticated ashlar side walls and simple latticed wrought-iron railings. The doorcase is particularly fine: it features a wide Roman Doric order with engaged columns distyle in antis, a triglyph frieze with guttae and mutules (unusually furnished with sets of guttae), and a pediment with similar mutules. The round-headed doorway contains double doors and is flanked by narrow sashed side windows. Above the pediment sits a small two-light casement flanked by single-light casements. The ground floor elsewhere displays tall eight-pane sashed windows with ornamental blind-hoods, while the first floor has nine-pane sashes. The façade is finished with a dentilled cornice and a hipped roof with three inserted dormers and two ridge chimneys.

The four-bay left return wall has its ground floor largely obscured by extensions; the first floor carries two six-pane sashes flanked by blind windows. The six-bay right-hand return wall features a full-height canted bay in the third bay, with fenestration matching the front elevation. At the rear of this wing is a round-headed doorway to the right, sheltered by a semicircular porch approached by nine steps with elegant wrought-iron bar railings terminating in wreaths. To the left is one eight-pane sash; above are three nine-pane sashes.

The interior contains a notable entrance hall with a coved alcove on each side flanked by coved roundels containing busts, an Ionic screen distyle in antis, and a dentilled cornice. The fine open-well stone staircase features moulded soffits to the steps and two slender twisted balusters per tread. Behind the screen, a doorway with pedimented architrave leads to the principal reception room of the wing, which retains wall panels, a marble fireplace, and a dentilled cornice. Off the service passage to the left of the hall is a doglegged staircase with closed string and barley-sugar balusters, possibly surviving or re-used from an earlier building on the site.

In 1974–6, a substantial modern extension was added to designs by Michael Manser and Partners (job architects Vladimir Bogdanovich and Mark Ashmead, with Frank Dewar). This addition links the manor house to the stable block while making minimal physical or visual impact on the eighteenth-century fabric. The extension has a steel frame clad in mirror glass set in neoprene gaskets, raised on a brick and cobble plinth. It rises three storeys, with the upper floor set back and canted to reflect the sky. A projecting rendered lift shaft projects at the rear of the main building but was never used. The interiors are designed as open-plan offices around a central service core with flexible arrangements. The extension was considered a very elegant conservation solution and received an RIBA commendation in 1977.

Historically, Thorncroft was one of two feudal manors of Leatherhead from Norman times, held by Merton College, Oxford, from 1266 to 1904. A timber-built house on the site, rebuilt in 1497, was occupied in the 16th and 17th centuries by Robert Gardiner, Sergeant of the Wine Cellar to Elizabeth I. The present house was taken down and rebuilt in its current form in 1776. The landscaped park is attributed to Lancelot Brown, though this attribution remains unsubstantiated.