Chicago-headquartered Kirkland & Ellis is earning £422 million from its London office, while Los Angeles-based Latham & Watkins is earning £341 million — both ahead of the highest-earning domestic firm, Linklaters, on £263 million.

Allen & Overy, which has since merged into A&O Shearman, was in fourth place on £214 million, followed by New York firm Simpson Thacher & Bartlett on £204 million.

Researchers at The Lawyer say their findings serve as “evidence of the Americanisation” of the legal market in the City of London.