He has become a prominent financial backer of Reform after previously being a Conservative donor.
He has donated hundreds of thousands of pounds to Reform, according to Electoral Commission data, including £192,000 between April and June this year.
Most of Mr Haidar’s properties are being advertised off-market rather than being publicly listed for sale.
However, Mr Haidar is having to contend with a wider slump in London’s luxury housing market. He said he had so far sold two properties but that “things are very, very, very slow”.
“It’s a buyer’s market but people are still not buying,” he said.
Figures from LonRes showed London’s most expensive neighbourhoods endured their worst August selling season since 2008, with deals down 19pc year-on-year.
A Treasury spokesman said it does not comment on any individual’s affairs.
