Dorothy Bentinck, Duchess of Portland

By Lauren Gilbert

Portrait of Dorothy Bentinck, c 1772
by George Romney

She was born Dorothy Cavendish, daughter of William Cavendish IV, the Duke of Devonshire, and his wife Charlotte Elizabeth Boyle, on August 17, 1750, in Devon. On November 8, 1766, at age 16, Dorothy married William Henry Bentinck, who was already the third Duke of Portland, in St. James, Westminster. He was 12 years her senior. You can read more about the Duke (here) and (here). Dorothy brought 30,000 pounds to the marriage.

The Duke of Portland was a Whig politician who held multiple offices, including two terms as Prime Minister (1783-1784 and 1807-1809). It is interesting to note that William Bentinck had his name legally changed to Cavendish-Bentinck in 1801. They had several children, four boys and two or three girls. Dorothy died June 3, 1794, at the age of 43, in London and was buried at St. Marylebone Churchyard, also in London. These are the facts most often found when Dorothy, the Duchess of Portland is mentioned. And yet... There are circumstances that make me believe there is more to Dorothy than her birth, marriage, children and death. 

Family correspondence is maintained at the University of Nottingham, which has an on-line search feature. Unfortunately, the actual letters themselves are not available. There is a very brief summary of the material covered in each of the letters in the collection, which is tantalizing.

William Henry Cavendish-Bentinck
3rd Duke of Portland
by John Powell after Joshua Reynolds

Dorothy’s mother-in-law was Margaret Cavendish Harley, wife of the second Duke of Portland. By all accounts, this duchess was a woman of wide interests: art, botany, books, sea shells, bees and gardens, especially roses. She was quite wealthy so was able to indulge her passions, and she formed friendships within the scientific community. She was also known in court circles and close friends with Mary Delany (see the earlier post: Mary Delany, Artist and Personality). 

Margaret’s home was open to scholars, artists and others of wide-ranging interests. Her collections were legendary. Margaret was a member of the Blue Stocking Society, a group of upper class women interested in education, literature and the arts, which included Fanny Burney, Elizabeth Montagu, Mary Delany, Hannah Moore and others. 

Letters from Margaret, 2nd Duchess of Portland to her son, in the collection at the University of Nottingham indicate Margaret approved of Dorothy, and accepted the invitation to attend their wedding. It is impossible to believe that her son’s wife would have had no exposure to the dowager duchess’s interests and acquaintances.

Duke and Duchess of Portland and Lady Mary Wortley Montagu
by George Vertue 1739

Another circumstance was a matter of family. Dorothy’s brother William Cavendish became Duke of Devonshire in 1764. He married Lady Georgiana Spencer June 7, 1774 in a secret ceremony. Dorothy was one of the five people in attendance. 

It appears that she and Georgiana became friendly; they certainly shared an interest in Whig politics. She is known to have canvassed for votes with Lady Jersey, the Duchess of Devonshire, and other ladies, dressed in the Whig colours of blue and buff with Fox regalia. Dorothy was included in at least one lampoon by Rowlandson: one entitled “The Two Patriotic Duchess’s on their Canvass” done in 1784 definitely included her (Dorothy was the one being rejected, while Georgiana was being kissed). 

Although I found no indication that Dorothy, Duchess of Portland, was an active social member of the Devonshire House set, as a family member, she was certainly “in the know” and involved in intimate family concerns to some degree. She wrote quite firmly to Lord Duncannon’s behaviour to his wife Harriet (Georgiana’s sister), an action that would seem most inappropriate unless there was a significant personal connection, and one that required a level of personal confidence and courage, given that husbands could legally treat their wives almost any way they chose at this time.

Ironically, most of the information I found about Dorothy Bentinck, Duchess of Portland, was indirect. I can’t help but speculate on her thoughts, opinions and interests. The letters suggest she enjoyed life in the country. She liked to ride when her health permitted. She was interested in cattle, and was involved in the decision to enclose common land on one of their estates (which apparently caused grave concerns among local people). 

She was also a social person; she and her husband entertained the Walpoles and others in their home, and visited them as well. She was a woman of means and privilege, surrounded by fascinating people. Her husband’s position as a Whig politician and her relationship with the Devonshire set gave her insight and access to some of the most interesting and influential politicians of her day. 

One can't help but feel that the hints provided in the summaries of the letters are just the tip of the ice berg.

Sources include:

The Things That Catch My Eye. “Regency Personality Series-William Henry Cavendish-Bentinck 3rd Duke of Portland 14 April 1738-30 October 1809” by David William Wilkin. March 23, 2014. HERE

English Historical Fiction Authors. “Mary Delany, Artist and Personality” by Lauren Gilbert. May 4, 2012. HERE

University of Nottingham UK. “Biography of Margaret Cavendish-Bentinck, Duchess of Portland (1715-1785).” No author or date. HERE

University of Nottingham UK. Manuscripts and Special Collections. Correspondence concerning the 3rd Duchess of Portland HERE

Hayden, Ruth. MRS DELANY Her life and her flowers. London: British Museum Press, 1980.

Foreman, Amanda. GEORGIANA Duchess of Devonshire. New York: Random House, 1988.

The Peerage. “Lady Dorothy Cavendish.” Last edited June 2, 2014. HERE

The Peerage. “William Henry Cavendish-Bentinck, 3rd Duke of Portland.” Last edited May 6, 2011. HERE

Victorian Web. “William Henry Cavendish Bentinck, 3rd Duke of Portland (1738-1809)” by Marji Bloy, PhD. HERE

Pictures from Wikimedia Commons:

Dorothy: HERE

William: HERE

The Duke & Duchess of Portland and Lady Mary Wortley Montagu HERE

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Lauren Gilbert lives in Florida with her husband, where she is working on the completion of her second novel, A RATIONAL ATTACHMENT. Her first, HEYERWOOD A Novel, was released in 2011. Visit her website HERE for more information.