British property developer Nick Candy attended the Abu Dhabi-led meeting and told Bloomberg, which first reported the events: “We are going to have the biggest talent brain drain this country has ever seen. And they won’t come running back.”

Financial advisers have seen a surge in the number of wealthy clients preparing to leave the UK after Labor won the general election and approved plans to abolish the non-dom regime that offers generous tax breaks to foreigners.

International tax consultant David Lesperance said he was “very busy” working with candidates considering a move. He said many people were making plans after hopes that Labor would not advance their proposals “disappeared like morning mist in the midday sun”.

“A growing number of people were exploring options in Spain and Portugal, which both offer attractive tax regimes,” said Tim Stvold, a partner at accounting firm Moore Kingston Smith. “The frequency and urgency of the questions are increasing.”

UK residents and non-residents do not currently need to pay local tax on foreign earnings for up to 15 years. The government will abolish the regime next April and replace it with a limited grace period.

Special tax treatment has long been a source of controversy because it predominantly benefits wealthy foreigners; but supporters of the tax cut argued that it kept wealthy individuals in Britain, where they would then spend their money.