London’s Losing Millionaires — but Holding on to Their Billions

London’s days as the home of the world’s wealthiest may be numbered — but their billions aren’t going anywhere.

Fresh data from With Intelligence, which tracks family offices and global capital flows, shows London remains one of the world’s top family office hubs, even as ultra-rich residents decamp for friendlier tax regimes.

The UK government’s April overhaul, which now subjects non-domiciled residents to a 40% inheritance tax on worldwide assets, has already triggered a wave of billionaire relocations to Monaco, Switzerland, the UAE, and beyond.

But their money managers aren’t budging.

Of the 259 single-family offices (SFOs) registered in the UK, controlling more than $344 billion in assets, nearly four in five are staying put, With Intelligence said.

That includes some of Britain’s most high-profile billionaires.

Lakshmi Mittal, the steel magnate behind ArcelorMittal, is heading to the UAE, while Richard and Ian Livingstone, the real-estate brothers, are off to Monaco.

John Fredriksen, the Norwegian shipping tycoon, is eyeing a move to Dubai.

Yet, in each case, their respective family offices — LK Advisers, London & Regional Group Properties, and Seatankers Management — remain anchored in London.

Of the 52 UK-based family offices linked to non-doms, only one is known to be leaving: NNS Advisers, run by Egyptian billionaire Nassef Sawiris. It is relocating to Abu Dhabi and has an estimated $2.5 billion to $5 billion under management, per With Intelligence’s data.

“Private capital is attracted to where the strongest support ecosystem exists,” Alastair Graham, director of family offices at With Intelligence, told Business Insider, citing investment management capability as “the most important factor for family offices.”

“The UK is the clear leader: it is the largest asset management hub in Europe, with a 36% market share, way ahead of France, Germany, and Switzerland.”

A record millionaire exodus

The resilience of London’s family offices contrasts sharply with the broader wealth migration picture.

According to the Henley Private Wealth Migration Report 2025, Britain is on track to lose a record 16,500 millionaires this year – more than any other country in the world and more than double the projected outflow from China, which has topped the rankings for a decade.

Analysts point to a combination of higher taxes, post-Brexit uncertainty, and tighter rules for investor migrants. The UK, they warn, risks losing both its residents and its reputation as a magnet for global wealth.

London’s sticky advantage

London’s edge comes from its dense network of specialist lawyers, wealth managers, tax experts, and investment professionals.

Graham added that UK-based family offices also benefit from the presence of 180 foreign and domestic banks and a major network of private client law firms, making London Europe’s “leading” financial center.

For many billionaires, moving their personal residence may save them a tax bill, but uprooting their financial infrastructure isn’t worth the hassle.

The city’s influence extends further. Around 50 UK family offices, representing $81 billion in assets, are already run on behalf of non-UK residents.

That means some of the world’s richest don’t live in London but still choose to base their wealth management there.

“Among London family offices,” Graham said, “52% of their total assets under management, or $179 billion, come from non-domestic family offices — either those owned by non-doms or those owned by high-net-worth individuals who are not resident in Britain.”

Taken together, the numbers underscore a paradox: London may be shrinking as a place where the ultrawealthy want to live, but it’s entrenched as the place where they want their fortunes managed.

Still, Graham cautioned that future tax measures could unsettle the balance.

“Among the measures which rumour has it that Rachel Reeves may be considering for her November budget is a wealth tax in one form or another, but it’s well known that wealth taxes are complex to formulate and could be counter-productive if there is a risk they may cause more non-doms to flee,” he said.

Whether this “Wexit” — the so-called wealth exit — proves a turning point or just another scare, London’s grip on the fortunes of the ultra-rich remains intact — at least for now.