Osterley was built in red brick around a quadrangle in 1577 for Sir Thomas Gresham, a merchant adventurer, founder of the Royal Exchange, and financial advisor to Queen Elizabeth I. Having no heir, Osterley passed to Gresham's step-children, who sold the estate in 1655. In 1684 Osterley was purchased by Dr Nicholas Barbon, who took a large mortgage on the property with the banker Francis Child. Francis Child (1642-1713) had begun as a prosperous goldsmith, who then established the wealthy Child banking dynasty. In the hope of redeveloping Osterley, Barbon demolished a portion of the house before he ran low on funds. His mortgage repayments to Child were unforthcoming, and in 1690 proceedings were begun to repossesses Osterley, ultimately bringing the entire estate into the ownership of the Child family in 1713.

Francis Child's sons, Sir Robert, Sir Francis and Samuel, all made various alterations to the house, and his eldest grandson, also Francis Child, commissioned Joseph Wilton (1722-1803) to provide marble chimneypieces for the gallery in the west range, and the hall in the east range. For these chimneypieces, Wilton acquired designs from his friend Sir William Chambers (1722-96). Despite some confusion on this subject, it has been established by Harris that there is no evidence for Chambers himself working at Osterley. Between 1713 and 1760, all of these various alterations resulted in an irregular and piecemeal house, and in 1761 Robert Adam was commissioned by Francis Child to made designs to reduce, regularise and modernise the house.

It is possible that Adam had been introduced to Francis Child through his neighbour, the 1st Duke of Northumberland, Adam's patron at Syon, but it is more likely that the acquaintance was formed through Sir Francis Dashwood, Adam's patron at West Wycombe, with whom Francis and Robert Child both shared various business and political interests. However this came about, in 1761 Adam proposed drastic alterations to the fabric at Osterley, with the demolition of the east range, as well as the ends of the north and south ranges, leaving a U-shaped building. This scheme was rejected, and instead only the central portion of the east range was removed, and a new entrance hall created in front of the gallery on the west range. A decade later, Adam decided to fill this space in the east range with the famous open double portico. It has been suggested that Adam’s inspiration for the portico at Osterley came from Robert Wood's illustration of the Temple of the Sun at Palmyra, or from James Gibbs's (1682-1754) early eighteenth-century designs for Witham Park, Somerset, with which Adam had been familiar since 1762 when he made designs for that house.

It is not known how far this work had progressed when in the autumn of 1763 Francis Child suddenly died, and Osterley was inherited by his brother Robert Child (1739-82). Robert Child had been a partner in the Child banking firm from 1760. He succeeded his brother Francis as head of the firm, but he is not known to have taken an active role in the business. Instead, he served as MP for Wells from 1766 until his death in 1782. He was also a Director of the East India Company, serving as Chairman in 1715. Only two weeks after he succeeded his brother, Robert Child married Sarah Jodrell (1741-93), the daughter of Gilbert Jodrell of Ankerwyke House, Buckinghamshire. He continued to employ Adam, not just at Osterley, but also commissioned designs for his town house at 38 Berkeley Square. Adam also provided unexecuted designs for Upton House, Warwickshire, and following Robert Child's death in 1782, Adam designed his funerary monument for the Church of St Leonard in Heston.

At Osterley, Adam created a new sequence of interiors (see plan in Bolton, 1922, Volume I, p. 282). This was done over time, room by room, in the following order: first was the eating room in the north range; second was the drawing room in the south range; third was a new library in the north range to replace one recently completed by Francis Child in the demolished east range; fourth was a new entrance hall on the east front of the west range to replace the original hall - thought to have been located at the centre of the demolished east range; fifth was the great staircase in the north range; sixth was the addition of pier glasses and girandoles in the gallery, which spans the full length of the west range; seventh, eighth and ninth were the rooms of the state apartment, the tapestry room, the state bedroom, and the Etruscan dressing room, designed simultaneously, and arranged in an enfilade within the south range. According to Harris, the state apartment of tapestry room, state bedroom and Etruscan dressing room was 'conceived in 1772 as a unit, composed of a sequence of different styles - French, English, and Italian - and different colours - red, green and pale blue - alluding to the elements: fire, earth and air, with pier glasses representing water.' Later, Adam also made designs for furniture for the breakfast room in the north range, and the taffeta bedroom on the bedroom storey of the north range, as well as a ceiling design for the octagonal vestibule under the external stairs on the west front, and a handful of buildings within the park. The drawings for the interior decoration at Osterley are catalogued here by room, and in accordance with the order in which these rooms were designed by Adam.

The plasterwork at Osterley has been attributed to Joseph Rose (although this is only documented in the entrance hall); much of the furniture was by William and John Linnell; and decorative paintings were carried out by Antonio Zucchi, Giovanni Battista Cipriani, and Pietro Borgnis. Adam's resulting rooms famously earned the approval of Horace Walpole, who in 1773 described the house (so far as it existed at that date) with rapturous enthusiasm in a letter to Mary Granville, Mrs Delany: 'oh, the palace of palaces! [...] so improved and enriched that all the Percies and Seymours of Sion must die of envy [...] There is a hall, library, breakfast room, eating room, all chefs-d'oeuvre of Adam, a gallery one hundred and thirty feet long and a drawing room worthy of Eve before the Fall.' Unfortunately, Walpole's second visit of 1778, and his observations of the newly formed state apartment, caused a change of heart.

Two months before Robert Child died, his only offspring, Sarah, eloped with John Fane, 10th Earl of Westmorland. On his death, Robert Child vested his entire fortune and property in his wife, also Sarah, who then married Francis Reynolds, 3rd Baron Ducie in 1791. Following Lady Ducie's death in 1793, Robert Child's estate - at his own behest - was then placed in trust for his eldest granddaughter, Lady Sarah Sophia Fane (1785-1867), who was not born until three years after her grandfather had died. In 1804 Sarah Sophia came of age, inherited the Child fortune - including Osterley - and married George Bussy Villiers, 5th Earl of Jersey. Osterley then remained in the possession of the Earls of Jersey until 1949, when the 9th Earl (1910-98) gave the estate to the National Trust. From 1947 the house had briefly been used as a hospital for the convalescence of injured airmen, but it was then opened to the public. It was administered by the V&A Museum until 1991, when it reverted to the care of the National Trust.

There are 33 Adam office drawings for Osterley within the National Trust drawings collection at Osterley Park. These include drawings for alterations to the fabric of the house, the interior, and buildings within the park.

See also: 38 Berkeley Square, Upton Park, and Church of St Leonard, Heston: monument to Robert Child

Literature:
R. & J. Adam, The works of Robert & James Adam, Volume II, part iv, pl. viii, Volume III, 1982, pl. ix; A.T. Bolton, The architecture of Robert and James Adam, 1992, Volume I, pp. 279--302, Volume II, Index pp. 25, 66; J. Lees-Milne, The age of Adam, 1947, pp. 104-106; E. Harris, The furniture of Robert Adam, 1963, pp. 37, 51, 67-68, 70, 71, 74, 75, 78, 81, 83, 84, 86, 92, 93, 95, 96, 98, 100, 101, 103; D. Stillman, The decorative work of Robert Adam, 1966, pp. 22-23, 25, 34, 59-60, 68-70, 75-76, 82-83, 88-89, 97-98, 109-110; D. Yarwood, Robert Adam, 1970, pp. 129-131, 197-199; M. Tomlin, Catalogue of Adam period furniture, Victoria & Albert Museum, 1972, pp. 14-100; G. Beard, The work of Robert Adam, 1978, pp. 40-43, 57-58; H. Hayward, and P. Kirkham, William and John Linnell: eighteenth-century London furniture makers, 1980, Volume I, pp. 113-120; J. Hardy, and M. Tomlin, Osterley Park House, 1985, pp. 13-108; A. Rowan, Catalogues of architectural drawings in the Victoria and Albert Museum: Robert Adam, 1988, pp. 62-83, 100; B. Cherry, and N. Pevsner, The buildings of England: London 3: northwest, 1991, pp. 438-342; J. Morley, 'Rich, chaste and Etruscan', Country Life, 9 May 1991, pp. 72-75; S. Jackson, 'Drawings in the Adam volumes relating to Osterley Park house', unpublished catalogue in the archive of Sir John Soane's Museum, August 1993; E. Harris, Osterley Park, Middlesex, 1994, pp. 24-28; J. Cornforth, 'Applause from the galleries', Country Life, 2 January 1997, pp. 31-32; L.R. Wilson-North, and S. Porter, 'Witham, Somerset: from Carthusian monastery to county house to Gothic folly', Architectural History, Volume 40, 1997, p. 96; S. Astley, The castles of Robert Adam, 2000, p. 34; T. Knox, and A. Palmer (ed.), Aspects of Osterley, 2000, pp. 6-72; E. Harris, The genius of Robert Adam: his interiors, 2001, chapter 10; D. King, The complete works of Robert & James Adam and unbuilt Adam, 2001, Volume I, pp. 28, 179, 184, 194-198, 234, 350-353, Volume II, pp. 132, 183, 224, 228, 232, 246; E. Harris, 'The colour of Adam', Country Life, 29 November 2007, pp. 106-109; E. Harris, The country houses of Robert Adam from the archives of Country Life, 2007, pp. 72-83; E. Harris, 'What would Vitruvius think? Robert Adam's designs for embroidery', National Trust historic houses collections annual, 2010, pp. 50-55; 'Child, Robert (1739-82), of Osterley Park, Mdx.', History of Parliament online; nationaltrustcollections.org.uk; Wikipedia.org/wiki/List_of_East_India_Company_directors

Frances Sands, 2014