Lady Kitty Spencer, 28, was photographed leaving The Mark Hotel in New York with boyfriend Michael Lewis, 60.
The pair were first rumoured to be dating last August but have remained coy about their relationship ever since.
Kitty previously dated 48-year-old property magnate Niccolo Barattieri.
The pair dated for four years before Barattieri left her in 2017 and began a romance with Liz Hurley.
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