Katherine Swynford and the Illicit Affair That Birthed Centuries’ Worth of British Monarchs

“She is my heart’s blood. My life. I want nothing but her.” 

So says John of Gaunt in the midst of a three-day bedroom bender with his newly widowed lover Katherine Swynford, as imagined by author Anya Seton in her 1954 historical novel Katherine.

Though the details of the tryst are fictional, Seton based her bestseller on a very real 14th-century love story—one that rivals the romance of Queen Victoria and Prince Albert and the scandal of then-Prince Charles and Camilla Parker Bowles (though with markedly less sordid receipts). 

Both couples owe a lot to Katherine Swynford, from whom “the Royal Houses of York, Tudor, and Stuart, and of every British sovereign since 1461” descended, as Alison Weir wrote in her 2009 biography Mistress of the Monarchy: The Life of Katherine Swynford, Duchess of Lancaster. “Without her, the course of English history would have been very different.”

House of Lancaster

In January 1328, King Edward III wed Philippa of Hainault, a self-governed holding of the Holy Roman Empire located mostly in modern-day Belgium. Among the sizable entourage that accompanied Philippa to England was Paon de Roët, a Hainaultian herald who would go on to become a knight and the father of Katherine Swynford (née de Roët). 

Key facts about Katherine’s birth—including when it was, where it was, and who her mother was—remain unknown, but it’s believed de Roëts welcomed their daughter into the world back in Hainault around 1350. At some point in the following few years, Katherine and her sister Philippa were entrusted to Queen Philippa to raise as courtly ladies of marriageable stock.

The siblings eventually made suitable matches: Philippa to none other than Geoffrey Chaucer; and Katherine, who may have been as young as 12 years old, to a knight some 10 years her senior. This Sir Hugh Swynford had two tumbledown Lincolnshire manors (but little money) to his name, and owed fealty to John of Gaunt, Duke of Lancaster—the third surviving son of King Edward III and Queen Philippa. As Katherine was working for Blanche, the Duchess of Lancaster, around the time of her betrothal, it’s possible that the Duke actually played matchmaker for the Swynfords. 

Katherine spent the next several years settling into domestic life as the lady of her own households and the mother of (at least) three children, all the while maintaining a presence in the Lancasters’ court. The Duke—and Sir Hugh beneath him—stayed pretty busy with more manly pursuits of the era; namely, starting and putting out various metaphorical fires as part of the Hundred Years’ War. 

It was during one of these military campaigns in France in 1371 that Sir Hugh perished, leaving Katherine alone to support their family. According to Weir, what likely began as an appeal to the Duke for financial assistance soon turned into a full-fledged affair.

Marriage Story

By that point, the Duke was on his second wife; his beloved Blanche had passed away in 1368, possibly due to complications from childbirth. Based on Chaucer’s elegy The Book of the Duchess—widely agreed to be about the death of Blanche—it seems that the Duke sincerely loved his wife and was distraught over her loss. Historians believe his grief is reflected in the lament of a dramatically woeful knight in the poem:

“I have of so grete won,
That Joye get I never non,
Now that I see my lady bright
Which I have loved with al my might,
Is fro me dedd, and is a-goon.
And thus in lefte me alone.”

That said, he managed to move on well enough to remarry in September 1371, this time for overtly political gain. His new wife, Constance, had a claim to the Castilian throne, and the Duke planned to fight for her right to sit on it (and, needless to say, for his right to sit beside her). 

How this timeline entwines with that of the Duke and Katherine’s early relationship is murky at best. What records do show is that on May 1, 1372, the Duke paid Katherine a then-considerable allowance of £10—the first of many gifts and grants that greatly surpassed what a nobleman was expected to provide for a fallen knight’s family. This paper trail of above-average attentiveness suggests that Katherine and the Duke began their romance that spring.

Sometime in the next year or so, Katherine became the governess of the Duke’s daughters with Blanche and also gave birth to her own child with him: John Beaufort. By the end of the decade, the couple had expanded their illicit brood to four, including Henry, Thomas, and Joan. With her impeccable upbringing and studied experience with managing the children of high-born women, Katherine headed up this 14th-century version of a blended family with apparent aplomb.

“She helped to bind Lancastrians, Swynfords, Beauforts and Chaucers into a harmonious family group, which in itself is testimony to Katherine’s warmth and generosity of character,” Weir wrote for the BBC’s History Extra.

Unsurprisingly, not everyone found the situation quite so delightfully progressive: The Duke’s detractors branded Katherine an “unspeakable concubine,” a “she-devil,” and just about everything in between. After the Peasants’ Revolt of 1381, in which overtaxed and underpaid laborers tore down the Duke’s Savoy Palace and clamored for his execution, he consciously uncoupled from Katherine and redoubled his (never fruitful) efforts to restore Constance to the Castilian throne.

But it wasn’t over between the lovers, owing in part to those four kids they had—and also because they didn’t actually cut off contact. Within two years of John’s return to England in 1389, Katherine was once again parking her horses in his stables (not a euphemism).

The Descendants

When Constance breathed her last breath in 1394, John and Katherine finally got the chance to make their family official in more ways than one. The amorous twosome tied the knot in 1396 and then legitimized their children by procuring approvals from both the monarchy and the pope.

Unfortunately, this happily-ever-after chapter would be the shortest in their entire love story. The Duke soon entered a period of ill health from which he’d never recover; he passed away in February 1399 at 58 years old. His “very dear wife and companion,” as he called her in his will, followed him to the grave four years later.

Though Katherine Swynford’s name might not be particularly well-known outside the circle of scholars and royal family enthusiasts, her descendants could hardly be more famous. Mary, Queen of Scots, Charles I, Charles II, co-sovereigns William III and Mary II, and everyone else in the House of Stuart descended from Katherine’s granddaughter Joan Beaufort and James I, King of Scots. The Hanovers (including Queen Victoria) and the Windsors (including Queen Elizabeth II and King Charles III) are also related to Katherine through this line.

Cecily Neville—the daughter of Katherine and John’s only daughter, Jean—married Richard Plantagenet, Duke of York, and they became the parents of Richard III and Edward IV, the maternal grandfather of Henry VIII. Katherine is actually related to Henry VIII on the other side, too: His father, Henry VII, is her great-great-grandson through her son John Beaufort.

You could make the argument that if you trace various genealogical splinters back far enough, there’s a good chance you could land on a branch, however distant, linking practically any two notable figures in history. (Katherine has also been connected to six U.S. presidents, including George Washington and both Georges Bush.) 

But the reason Katherine Swynford’s formidable family tree seems so extraordinary is because she herself wasn’t originally a notable figure; she was a mistress with four illegitimate children. Through ample tact and a remarkable aptitude for playing the long game, she elevated herself from a future footnote in John of Gaunt’s biography to a treasured wife who ended up shaping the monarchy for centuries to come.