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Bentinck, Margaret Cavendish [née Lady Margaret Cavendish Harley], duchess of Portlandfree

  • Pat Rogers

Margaret Cavendish Bentinck [Lady Margaret Cavendish Harley], duchess of Portland (1715–1785)

by Joseph Brown, pubd 1861 (after Christian Friedrich Zincke, 1738)

Bentinck, Margaret Cavendish [née Lady Margaret Cavendish Harley], duchess of Portland (1715–1785), collector of art and natural history specimens and patron of arts and sciences, was born on 11 February 1715 in London, the only surviving child of Edward Harley, later second earl of Oxford (1689–1741), and his wife, Henrietta Cavendish Harley (1694–1755), daughter of John Holles, duke of Newcastle upon Tyne (1662–1711), and Lady Margaret Cavendish (1661–1716). The marriage of Margaret's parents in 1713 had been eagerly sought by the bridegroom's father, Robert Harley, first earl of Oxford. The bride brought with her great wealth, along with the Cavendish estates.

Margaret Harley soon became a favourite of the literary circle surrounding the Harleys. Matthew Prior addressed verses to her when she was five beginning, 'My noble, lovely, little Peggy', which have often been described as the finest poem to a child in English. As an infant Margaret was painted with her mother by Bernard Lens III (1681–1740), who subsequently gave her art lessons. To her marriage, on 11 June 1734, to William Bentinck, second duke of Portland (1709–1762), she brought a dowry of £20,000, about half the value of her husband's estates. Her parents had considered many offers made to them for her hand, and fixed on Portland as the candidate least prone to fashionable vices. Fortunately for the marriage, the duke, unlike Margaret's father and two sons, managed to avoid ruinous expense.

The couple settled at Bulstrode, near Gerrards Cross in Buckinghamshire, where the duchess paid special attention to the gardens. For the next fifty years she devoted her time and energy, and much of her wealth, to the formation of an immense collection embracing natural history, in its broadest sense, and the fine arts, stored at Bulstrode. It was, eventually, the largest in Britain, and possibly in Europe, exceeding that of Sir Hans Sloane deposited in the British Museum. She developed a passion for botany and cultivated the friendship of the plantsman Philip Miller (1691–1771) and the botanical illustrator Georg Dionysius Ehret (1708–1770), who produced for her many of his most notable paintings of British plants. She also employed John Lightfoot (1735–1788), the naturalist, as chaplain and librarian. Together they created a herbarium, now at Kew. One of her special interests lay in seashells: through Peter Collinson (1694–1768) she obtained drawings of American shells by William Bartram (1739–1823). Her fondness for botany also brought her into contact with Joseph Banks and Daniel Solander, who visited her after their return from Cook's first voyage. The duchess kept bees and hares, as well as maintaining an aviary and a menagerie.

To care for her five surviving children (a daughter was to die aged sixteen), the duchess employed Elizabeth Elstob (1683–1756), the pioneering Anglo-Saxon scholar, as governess from 1739 until her death. From the age of seventeen Margaret had been on close terms with Elizabeth Robinson (1720–1800), better known as Mrs Montagu, 'Queen of the Blues'. Together they engaged in many pursuits, intellectual and social, until their relationship declined about 1753. Another friend was the poet Edward Young (1683–1765), for whom the duchess tried unsuccessfully to obtain a deanery from the duke of Newcastle. Young was likewise unable to persuade her into admiring the novels of his friend Samuel Richardson; late in life she expressed her much greater delight in Fanny Burney's work Cecilia (Diary and Letters, 2.254).

Mary Delany (1700–1788) was a close friend from youth. Through Mary's brother, who lived near Wootton Hall, Northampton, the duchess met and generously befriended Jean Jacques Rousseau who took refuge there for a few months in 1766–7. She sent him plants and books, and in September 1766 he joined her on an expedition to the Peak District in search of wild plants. After the death of the duke in 1762 and of her own husband in 1768, Mrs Delany passed every summer at Bulstrode, where in 1772 she devised her method of cutting flowers in paper, allegedly deceiving the duchess with her initial collage into taking it for a real geranium. The two women botanized and ornamented a grotto at Bulstrode with an ever-increasing collection of shells. The duchess spent her winters in London, where she created a 'museum' of natural curiosities at her house in the Privy Garden, Whitehall. She also made Mrs Delany an interest-free loan of £400 to enable her friend to buy a house in London.

The most famous item in the duchess of Portland's huge collection was acquired in 1784, when she bought the so-called Portland vase from Sir William Hamilton. The vase, previously known as the Barberini vase, was and remains 'an outstanding example of ancient Roman glass using the cameo technique' (Stourton), made up of several layers of coloured glass which were then cut and decorated, in this case to show six figures in two mythological scenes. The vase probably dates from the early first century AD. The duchess paid £2000 for the vase and three other items; sold at her death, it was bought back by the third duke for £1029. The vase was loaned in 1810 to the British Museum, where it remains.

The duchess died at Bulstrode after a short illness on 17 July 1785. Mary Delany was left to the kindness of George III and Queen Charlotte, who had often visited Bulstrode, as well as receiving the duchess at Windsor. The duchess's huge collection of works of art and virtu was disposed of at a sale in 1786 lasting thirty-eight days. The aim was to recoup the family fortunes, drained by the electioneering expenses of her elder son and the high living of the younger. Four of the duchess's children survived to adulthood: Elizabeth (1735–1825) married Thomas Thynne, later first marquess of Bath (1734–1796), and was lady of the bedchamber to Queen Charlotte; Henrietta (1737–1827), married George Grey, later fifth earl of Stamford (1737–1819); the statesman, William Henry Cavendish Cavendish-Bentinck, third duke of Portland (1738–1809), married Lady Dorothy Cavendish (1750–1794), daughter of the fourth duke of Devonshire; and Edward Charles (1744–1819) married Elizabeth Cumberland (d. 1837).


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  • U. Nott. L., corresp. and papers
  • BL, letters to Thomas Birch, Sir Hans Sloane, and others
  • Hunt. L., Montagu MSS


  • B. Lens, double portrait, 1717 (with her mother)
  • M. Dahl, pastels, 1723; formerly at Welbeck Abbey
  • C. F. Zincke, enamel miniature, 1738, Welbeck Abbey
  • J. Brown, engraving, pubd 1861 (after enamel by C. F. Zincke, 1738), NPG [see illus.]
  • T. Hudson, portrait; fomerly at Welbeck Abbey
Historical Manuscripts Commission
H. Walpole, ed. W. S. Lewis & others, 48 vols. (1937–83)