A Mayfair mansion with a footnote in American history has quietly rejoined the London market. The Grade II–listed Edwardian townhouse, priced at £25 million (about $34 million), was once the London base of the Auchincloss-Coats family, relatives of Jacqueline Kennedy Onassis through her stepfather, Hugh D. Auchincloss Jr. It’s the first time the house has been offered for sale in more than 30 years.

In the summer of 1951, Auchincloss sent his stepdaughters—Jackie, then 22, and Lee, 18—to Mayfair to kick off a months-long grand tour of Europe. Upper Brook Street served as their London landing pad before stops in Paris, Rome, Venice, and Florence. However, what the sisters thought of their digs wasn’t recorded.

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The house itself dates back further. It was commissioned in 1908 by American industrialist James Monro Coats, heir to the J & P Coats textile fortune and a member of the Auchincloss banking dynasty. Designed by Arnold Bidlake Mitchell, whose clients included royalty and financiers, the residence was meant to read as a statement—an American Gilded Age sensibility translated into Mayfair stone.

Inside, the rooms shift in mood rather than marching in lockstep. There are formal neo-Georgian spaces, French Neo-Rococo drawing rooms, and highly detailed Arts & Crafts interiors that once held Coats’s private office and cigar lounge. Over the years, guests reportedly included neighbor Ernest Cassel, social figure Edwina Ashley (later Countess Mountbatten of Burma), and architect Edwin Lutyens.

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By the mid-20th century, the mansion’s social life had quieted. The building was converted into offices and later became the London home of an international bank. Now it’s at another pivot point. Westminster planners have indicated support for a return to residential use, giving a future owner the chance to reimagine the property as a private home. The townhouse spans nearly 14,000 square feet, anchored by a central courtyard garden and a separate mews building tucked behind.

“The provenance of this Mayfair mansion building offering views onto Hyde Park is outstanding,” says Peter Wetherell, whose firm is marketing the property alongside Knight Frank. Agents say a restored version could command a substantially higher valuation, reflecting how few large historic houses remain in Mayfair.

Click here to see more photos of this Mayfair home.