Soros used Quantum Fund in 1992 to bet successfully that sterling was over-valued against the Deutsche Mark, forcing then-Prime Minister John Major to pull the pound out of the European Exchange Rate Mechanism (ERM).
Soros, who was born in Hungary but made his way to London as Communists consolidated power in Budapest, said economic reality was starting to catch up with a United Kingdom that voted 52 to 48 percent to leave the European Union in a June 23 referendum.
"The moment of truth is fast approaching," Soros said in an article emailed to reporters.
"The fact is that Brexit is a lose-lose proposition, harmful both to Britain and the European Union. It cannot be undone, but people can change their minds."
Britain's $2.5 trillion economy has shown resilience since last year's referendum although sterling fell 25 cents against the dollar in the hours immediately after the shock vote.
But Britain went from being one of the fastest-growing economies of the Group of Seven leading economic nations in 2016 to the slowest in early 2017, as the fall in the value of the pound after the Brexit referendum pushed up inflation and hit consumer spending.
The combination of rising prices and slowing wage growth represents a challenge for the Bank of England and its top policymakers, three of whom voted last week to raise interest rates to head off the acceleration of inflation.
Soros said the Bank had underestimated the impact of inflation and was now catching up.
Britain has less than two years to negotiate the terms of the divorce and the outlines of the future relationship before it is due to leave in late March 2019. Both sides need an agreement to keep trade flowing between the world's biggest trading bloc and the fifth-largest global economy.
Soros said that if Prime Minister Theresa May wanted to stay in power, she would have to change her approach and take account of young people who he said wanted to find well-paying jobs.
She should, Soros said, seek to keep Britain in the EU's single market as Britain tried to extract itself.
"The divorce process would take at least five years to complete, and during that time new elections would take place," Soros said. "If all went well, the two parties may want to remarry even before they have divorced."
(Editing by Hugh Lawson)
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
Election Results for Lok Sabha Election 2019 will be out on May 23. Get the latest election news and live updates on ndtv.com/elections. Catch all the action on NDTV Live. Like us on Facebook or follow us on Twitter and Instagram for news updates from each of the 543 parliamentary seats for the election 2019