A portrait of George IV’s favourite mistress and the woman he illegally married is going on show at Buckingham Palace.

George, Prince of Wales, who was famous for his extravagant lifestyle, became infatuated with Maria Fitzherbert, who was twice widowed, after meeting her when he was 22.

They were wed in secret a year later by a reverend whose debts George had paid off to secure his release from prison.

Drawings such as After James Gillray, Wife Or No Wife Or A Trip To The Continent allude to the illegal marriage of the Prince of Wales and Maria Fitzherbert
Drawings such as After James Gillray, Wife Or No Wife Or A Trip To The Continent allude to the illegal marriage of the Prince of Wales and Maria Fitzherbert (Royal Collection Trust/Queen Elizabeth II 2019)

George’s father, George III, did not consent to the marriage and it was deemed invalid.

The Prince of Wales went on to marry his cousin, Princess Caroline of Brunswick, in 1795 in exchange for Parliament paying his debts.

He hated his wife, banned her from his coronation and wrote a will which would have left her with one shilling and given Fitzherbert the rest.

The couple lived together for about a year before George sought a separation.

He remained largely devoted to Fitzherbert, “the wife of my heart and soul”, despite having many mistresses and their relationship being ridiculed by the public.

After James Gillray, The Morning After Marriage, Or A Scene On The Continent
After James Gillray, The Morning After Marriage, Or A Scene On The Continent (Royal Collection Trust/Queen Elizabeth II 2019)

George commissioned artist Richard Cosway to make the pencil drawing of Maria in 1789 for the equivalent fee of £42.

The royal, who became king in 1820, had not paid his principal painter the sum when he died in 1830 and was buried with a miniature portrait of Fitzherbert around his neck.

The portrait has been acquired for the Royal Collection and will go on display at George IV: Art & Spectacle at Buckingham Palace in November.

Exhibition curator Kate Heard said: “Cosway’s work was much admired by George IV, who commissioned numerous portraits from him.

“This beautiful drawing is a wonderful example of the artist’s sensitive and fluid draughtsmanship, and also a reflection of the prince’s devotion to Maria Fitzherbert.”

George IV: Art & Spectacle is at the Queen’s Gallery, Buckingham Palace, from November 15 to May 3.