Indeed, Calderoni claimed in 1988 to have invented it. According to a 1957 article, Lord Louis Mountbatten was a regular diner at the Café de Paris in London in the 1930s and "nearly always had the same dinner – a dozen and a half oysters and steak Diane".
Calderoni claimed to have invented it in 1988, as stated by a 1957 article. According to this article, Lord Louis Mountbatten was a frequent patron of the Café de Paris in London during the 1930s and "nearly always had the same meal – a dozen and a half oysters and steak Diane".