Margaret Cavendish-Harley (February 11, 1715, Welbeck Abbey - July 17, 1785, Bulstrode, Buckinghamshire), was the richest woman in the Kingdom of Great Britain at her time.

She was a daughter of Edward Harley, 2nd Earl of Oxford and Mortimer, bibliophile, collector and patron of the arts, and Lady Henrietta Cavendish Holles (1694–1755), the only child and heir of John Holles, 1st Duke of Newcastle and his wife Lady Margaret Cavendish.

She grew up at Wimpole Hall in Cambridgeshire surrounded by books, paintings, sculpture and in the company of writers such as Alexander Pope, Jonathan Swift and Matthew Prior as well as aristocrats and politicians. As a child, Margaret collected pets and natural history objects (especially shells) and was encouraged by her father and her paternal grandfather, Robert Harley, 1st Earl of Oxford and Mortimer to do so.

At 20, on July 11, 1734, in Oxford Chapel, Marylebone, she married William Bentinck, 2nd Duke of Portland, her 'Sweet Will', and they later had six children:

1. Elizabeth Cavendish-Bentinck (Welbeck Abbey, June 27, 1735 – December 25, 1825, London)
2. Henrietta Cavendish-Bentinck (b. Welbeck Abbey, c. 1736)
3. William Henry Cavendish-Bentinck, 3rd Duke of Portland (1738–1809)
4. Margaret Cavendish-Bentinck (Welbeck Abbey, c. 1740 – April 28, 1756)
5. Frances Cavendish-Bentinck (Welbeck Abbey, c. 1742 – March 1743)
6. Edward Charles Cavendish-Bentinck (Welbeck Abbey, March 3, 1744 – October 8, 1819)

She was Dowager Duchess of Portland from her husband's death in 1761 until her own death in 1785.

By the November after her marriage her collecting had really gathered pace, expanding to include the decorative and fine arts as well as natural history. (She was already heiress to the Earl of Arundel collection.) Her home in Buckinghamshire, Bulstrode Hall, provided space to house the results, and her independent fortune meant that cost was no object (on her mother’s death in 1755 she also inherited the estates of Welbeck in Nottinghamshire). Bulstrode was known in court circles as ‘The Hive’ for the intense work done there on the collections by Margaret and her crack team of botanists, entomologists and ornithologists, headed by herself, Daniel Solander (1736-82, specialising in shells and insects) and Revd John Lightfoot (1735-88, her librarian and chaplain) - her collection was, unlike many similar contemporary ones, well-curated.

'The Portland Museum' at Bulstrode, also including a zoo, an aviary and a vast botanic garden, was open to visitors. Many came, scholars, philosophers, scientists and even Royalty, and the collection became a cause celebre. Her fellow collector Horace Walpole commented on it:

Few men have rivalled Margaret Cavendish in the mania of collecting, and perhaps no woman. In an age of great collectors she rivalled the greatest.”

or, in the words of Mrs Delaney:

“Surely an application to natural beauties must enlarge the mind? This house with all belonging to it is a noble school for contemplations!”

Her collecting was also encouraged by her creative milieu - Margaret, along with her eternal companion Mrs Delany, was a member of ‘The Bluestockings’, a group of aristocratic 'Enlightenment women' trying to get women intellectual independence in a form that would be acceptable within the period's social norms, by patronising and promoting learning and the arts (eg by presiding over London and country-house salons).

Her natural collection was the largest and most famous of its time, with little geographical bounds, including objects from both Lapland and the South Seas (she patronised James Cook and bought through dealers shells from his second voyage). She draw and recorded its specimens, sorting them innovatively in type species and displaying them alongside ancient remains such as the Portland Vase, which she bought from Sir William Hamilton.

Lightfoot later wrote in the introduction to the 1786 auction catalogue that it was her "intention to have had every unknown species in the three kingdoms of nature described and published to the world", but this was thwarted by Solander's death in 1783 and her own two years later. On her death, with her children uninterested in the collection, her son's political career to finance and her creditors' demands to be paid, it was her will that it be sold and it was entirely dissolved at auction from 24th April to 3rd July 1786. This auction was at her residence in Whitehall (which had also housed parts of the collection), was made up of over 4000 lots, and attracted hundreds of people. Some fine and decorative arts were bought back by her family at the auction, including the Vase and pieces from a silver-gilt dessert service Margaret had designed herself, crawling with exquisitely modelled insects. However, the vast majority went, including the whole natural history collection - Walpole records that only 8 days included items other than "shells, ores, fossils, birds' eggs and natural history". Only fragments of the Portland Museum's building survive too, since Bulstrode was demolished in the 19th century.

Sources and links

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• 2006 exhibition
• Another link to the exhibition
• R. G. W. Anderson (ed.), Enlightening the British : knowledge, discovery and the museum in the eighteenth century, ISBN 071415010X, p83

1715 births | 1785 deaths | Natives of Cambridgeshire | Collectors | Botanists | The Enlightenment | English antiquarians | Natural sciences | Natural history museums