A record number of millionaires could leave the United Kingdom this year as political turmoil and the potential for higher taxes under a future Labour government reduce the appeal of what was once among the top destinations for the rich. As many as 9,500 people with at least $1 million in liquid, investable assets, will leave the country, more than double the number that left in 2023, according to provisional estimates contained in a report Tuesday by migration advisers Henley & Partners.