Surging property prices and big returns in equity markets in recent years have combined with higher wages and employment rates to create more millionaires as the UK economy gets back on track.
The research shows that every UK region is now more affluent than it was five years ago, with measures including household wealth, gross domestic product (GDP), exam results, charitable donations and entrepreneurship taken into account.
Akshaya Bhargava, chief executive of Barclays Wealth and Investment Management, said: "The UK is becoming more prosperous, with every region having grown in affluence since 2010.
"It is also encouraging to see that regions and cities are starting to close the gap with London in terms of prosperity; with the North East, for example, seeing business growth rates behind only London."
London and the South East remain the most prosperous regions, while the capital also boasts the most millionaires – up 48% in the past five years to 191,000, which is more than the combined millionaire population of Wales, Scotland, Northern Ireland and Northern England.
The East of England is ranked third as rising house prices push more wealthy Britons outside of London, with 23,000 more millionaires now calling the East their home.
Reading is listed second for prosperity in the UK, according to the index, with average earnings of £30,562.
Growing numbers of entrepreneurs in the UK is also seen as another factor in increasing wealth, with Cambridge ranking third as it has emerged as a start-up hub.
The North East and Newcastle fall low on the prosperity index. But the study also showed the highest rate of growth in millionaires across the North East, alongside Wales, at a rise of 50% to 12,000 since 2010.
The study said Northern regions "may be on the cusp of change, with the North East leading the way".
Despite the jump in wealthy Britons over the past five years, the research said growth in millionaires is expected to return to more normal levels over the long term, with a 9% increase in the UK expected by 2025, in-line with GDP growth.
Here are the country's wealthiest cities ranked according to the prosperity index:
2. Reading 3. Cambridge
4. Birmingham 5. Bristol
6. Leeds 7. Cardiff
8. Manchester 9. Liverpool
UK's most expensive houses
UK millionaires double in five years
The most expensive property on the open market in London right now isn't even a house. But this five-bedroom apartment has the prestigious One Hyde Park address, with magnificent views of both Knightsbridge and Hyde Park. Like a country house, it's split into two wings, connected by a 50-metre hallway. And the Candy & Candy decor is dramatic, to say the least. It's priced at an eye-watering £64,999,950, through Savills.
This seven-bedroom house has both indoor and outdoor swimming pools, along with a spectacular double-volume entrance hall, panelled study and grand double reception room. There are also two large dining rooms, a cinema room and a staff flat on the lower ground floor. It costs £46,500,000 through Knight Frank.
This 18th-century house has its own spa tucked away in the basement, with swimming pool, gymnasium, steam room, sauna and beauty treatment suite. The "magnificent ambassadorial mansion" has six receptions, eight bedrooms and a separate mews house. It costs £39,500,000 through Savills.
This house may look in pretty good condition to you and me, but the agents reckon it "does require updating to meet today's standards". Built in 2001, Oaklands Park has over 100 acres of land with four cottages, 33 stables and a polo pitch. There are five reception rooms and six main bedroom suites. It's for sale through Savills for £25,000,000.
Just three miles from the middle of Edinburgh, sixteenth-century Craigcrook Castle is up for sale for the first time in nearly three hundred years. It needs a fair bit of work - and a great deal more money - but has gallons of potential. It's up for sale through Ballantynes with a guide price of £6,000,000.
The most expensive property we could find in Northern Ireland right now, Dundarave is a grand mid-eighteenth-century house standing in 595 acres. The extraordinary Great Hall, which rises to the full height of the building, was based on the hall of London's Reform Club. It's on the market for £5,000,000 with Savills.
It may be a little outside the usual footballer's territory, but Swettenham Hall has room for a good kickabout in several of its half-dozen reception rooms. There's an indoor swimming pool and gym, a historic chapel - and a helicopter hangar. It's up for sale with Jackson-Stops for £12,750,000.
This bastion of bling near Exeter was built four years ago and comes with an extraordinary range of features - from equestrian facilities to a helipad and hangar. There's an indoor swimming pool, an enormous garage that's more immaculate than most kitchens, and even an indoor shooting range - as well as a cinema, bar and entertainment suite. It'll set you back £7,000,000 through agents Knight Frank.
"Steeped in history and glamour", say the agents, this Georgian country pile has nine reception rooms and 13 bedrooms. Designed by by Sir John Soane, it features a sweeping double staircase and stunning original features. There's a rumour that Johnny Depp's interested, though, so you may need to move fast to snap it up. It's priced at £5,750,000 through agent Sowerbys.
Near Droitwich, this "faux-Regency house" has nine bedroom suites and four receptions - plus a huge conservatory and an orangery. It has a well-kitted out leisure wing, with pool, gym, sauna, steam room and solarium. Set in parkland, it's approached by an impressive drive. You can snap it up for £9,500,000 through agents Andrew Grant.