Sir Rowland Winn, 5th Baronet (1739-85), was the eldest son of the 4th Baronet, also Sir Rowland Winn, of Nostell Priory. In 1758 he married Sabine Louise, the daughter of Jacques Philippe, Baron d’Hervert, the Governor of Vevay, whom he had met during his Grand Tour. He briefly served as MP for Pontefract during 1768, only to be unseated following a petition prompted by his supporters having prevented opposing voters from reaching the poll.

The 5th Baronet succeeded his father in 1765, immediately employing Robert Adam to carry out works at Nostell Priory. A year later he purchased a five-bay, forty-four foot wide townhouse at 11 St James's Square. Numbers 9-11 St James's Square had been built by Benjamin Timbrell in 1735-36 as a speculative development, and replacing a large seventeenth-century house which had been built by the Earl of St Albans. As at Nostell, Thomas Chippendale was employed to furnish the house, and in 1774 Robert Adam - then nearing completion of the interior of Nostell - was commissioned to make a design to reface 11 St James's Square. The surviving drawing is one of two alternative designs provided to the 5th Baronet. The façade was executed in accordance with the extant drawing in 1774-76. The new façade included Adam's Spalatro order columns, but these were replaced with Corinthian capitals at some time during the nineteenth century. According to Pevsner, it was on this building that we can see the first known use of the Adams' patented Liardet's composition.

11 St James's Square was sold within one month of the 5th Baronet' unexpected death in a carriage accident in 1785. The 6th Baronet was still a small child of nine, and the sale helped to alleviate the financial difficulties caused to the family by prolonged building at Nostell. Alterations were made to the façade of 11 St James's Square in 1877 by Messrs Trollope and Sons, including the portico and balcony which remain in situ. Numbers 9-10 now house the Institute of Internal Affairs, and number 11 was restored in 1988-91 by the Thomas Saunders Partnership, and contains offices.

See also: Nostell Priory

Literature:
A.T. Bolton, The architecture of Robert and James Adam, 1922, Volume II, Index pp. 50, 91; Survey of London, volume 29, 1960, pp. 118-124, 133-134; D. King, The complete works of Robert & James Adam and unbuilt Adam, 2001, Volume I, pp. 264, 290-92; S. Bradley, and N. Pevsner, The buildings of England: London 6: Westminster, 2003, pp. 627-28; 'Winn, Sir Rowland, 5th Bt. (1739-85), of Nostell Priory, nr. Pontefract, Yorks.', History of Parliament online

Frances Sands, 2012