According to Odgers Berndtson, the range of nationalities has also expanded, with FTSE 100 chief executives made up of 20 different nationalities last year, compared to 11 in 2006.
Meanwhile, 30% of chairs and chief financial officers were also born overseas, making the UK one of the most internationally diverse business environments in the world.
In comparison, no other leading exchange had more than a third of non-nationals as chief executives - as few as 10% in the US and France.
“London has boomed post Big Bang and the millennium with increasing numbers of global businesses recognising its strength as a global business centre and choosing to establish a base here.
“The key question is how impending trade negotiations and deals with the US, EU, Asia and rest of the world will impact this trend in the future," Kester Scrope, chief executive of Odgers Berndtson, said.
The research did raise questions about the appeal of UK leadership talent overseas, as it found that, in comparison, only four chief executives from the biggest European and US companies analysed were British.
Another worrying trend for the UK is that the percentage of FTSE 100 companies headquartered in the UK also fell in the last years, from 97% in 2001 to 85% last year.
Kit Bingham, head of Odgers Berndtson’s chair and board practice in London, warned that there must be some concern about the UK’s ability to continue attracting the top corporate talent globally, especially at a time when it is looking to re-position itself in the world.
Last week, Tesco’s chairman John Allan was roundly criticised for saying that white men were becoming an “endangered species” in boardrooms. He argued that it was an “extremely propitious period to be female and from an ethnic background and preferably both”.
Yvette Copper, chair of the Home Affairs Select Committee, tweeted, “Says the man who chairs a board of eleven, eight of whom are white men!!! No words.”
The Equality and Human Rights Commission said last year that women were still being held back from senior posts and board positions due to the “old boys’ network” in company boardrooms. More than 60% of FTSE 350 companies and almost half of FTSE 100 companies were failing to meet the 25% target of female representation on boards.
The Parker Review report published in November said that the boardrooms of Britain’s leading public companies “do not reflect the ethnic diversity of either the UK or the stakeholders that they seek to engage and represent” with companies failing to promote enough ethnic minority employees to top executive positions.