Elizabeth, Lady Melbourne, was the mother of William Lamb, Queen Victoria’s first prime minister. While he was seen as the very essence of patrician Victorian respectability, his mother was notorious. A lady who refused to conform to the day’s standards of a ‘good’ woman of the time, she did what she had to do to get ahead in suffocating Georgian high society.

During her lifetime, Lady Melbourne was compared to the scheming Marquise de Merteuil, the siren in Pierre Choderlos de Laclos’ novel Dangerous Liaisons who used seduction as a social weapon. It was said by her circle of female Georgian friends that she could never look at a marriage without trying to wreck it.

Together with society celebrity Georgiana Cavendish, Duchess of Devonshire, and artist Anne Damer, she was portrayed as one of the three witches from Macbeth. In the portrait, the women float around a cauldron mixing spells to cast on their society friends. Disapproving society diarist Lady Mary Coke noted: “They have chosen the Scene where they compose their Cauldron but instead of ‘finger of Birthstrangled babe etc’ their Cauldron is composed of roses and carnations and I daresay they think their charmes more irresistible than all the magick of the Witches.”

But Elizabeth’s spells were far more dangerous than those Shakespearean sorceresses. She seemed to live by an unwritten rule that she encouraged the duchess of Devonshire to follow – that a lady had to be loyal to her husband until she provided him with an heir. After that, women were free to follow their own interests, just as their husbands did. Georgiana, under her influence, embarked on a disastrous love affair with the young Charles Grey, later Earl Grey, and she even secretly gave birth to his daughter while in exile on the Continent.