Prince of Wales Albert Edward (later King Edward VII of the United Kingdom)
Portrait by George Frederic Watts (link)
From Slate Magazine:
"In his profligate youth, the English Prince of Wales—Britain's future King Edward VII (he ruled between 1901 and 1910)—was a celebrity in Paris, thanks to his gargantuan appetites for both food and sex. Perpetually availed of champagne and cigars, his girth filled out by five high-protein meals a day, he would receive a standing ovation at the theater whenever he appeared with a beautiful new paramour on his arm.
"From 1877, Bertie kept an apartment in a building on the Avenue de l'Opéra, an address he relished because it was the Right Bank's upscale epicenter of vice, then dubbed by one British aristocratic roué, Lord Hertford, "the clitoris of Paris." He finally gave it up 27 years later, when he was crowned king, and the building changed hands several times before it became a hotel. Today, this loyal establishment names each suite after a consort of "Dirty Bertie," as the British nicknamed him, including actress Sarah Bernhardt, American socialite Jennie Churchill (Winston Churchill's mother), and courtesan Alice Keppel (great-grandmother of Camilla Parker Bowles).
"Even now, legends of Edward's appetites filter through Paris. One in particular stands out. According to Maisons Closes, or Shuttered Houses, the classic study of Paris' brothels written in 1958 by an eccentric French "historian of private habits" named Romi (real name Robert Miquel), the Prince of Wales grew so obese in middle age that he commissioned the construction of a fauteuil d'amour—a "sex chair"—to be kept in his favorite luxury brothel, Le Chabanais. This bizarre device allowed him to have sex without crushing the poor girl with his enormous bulk.
"The chair's provenance could be traced until 1951, when it sadly disappeared into the hands of private collectors."
A replica of the "love chair" (link)
I dunno, he doesn't look that fat to me, but perhaps he was by early 1900s standards. Or maybe the Parisian habitues of the brothels were a bit smaller than their Saxe-Coburg counterpart. And that chair looks like a fantastic idea.