The UK is home to more than 250,000 millionaires who are collectively worth £1.28 trillion, research has indicated.
An estimated 284,317 people have assets worth more than £1 million, excluding their main home, according to CoreData Research UK.
The average level of wealth among millionaires is £4.5 million, but the country is also home to a number of ultra-high net worth individuals, who have assets worth more than £30 million.
Fifty-five per cent of all UK millionaires have assets valued at between £1 million and £2 million.
The group found that the majority of millionaires' assets are held in shares at 34.2%, while 32.2% is invested in property and 13.2% is held in cash.
Just over 5% of their money is invested in physical items, such as antiques, collectables and art.
Craig Phillips, principal of CoreData Research UK, said: "Some may argue a large number of millionaires reflect a clear disparity in a society.
"However, many of Britain's modern-day wealthy are self-made and have become so through creating and running successful businesses, which bodes well for the economic health of the nation."