Britain's wealthiest people saw their fortunes rise to record levels last year, according to the annual Sunday Times Rich List (paywall), at a time when most Britons' earnings and savings were squeezed by inflation and low interest rates. The combined wealth of Britain's 1,000 richest people swelled by almost 5% to more than £414bn, the highest recorded by the 24-year-old survey.

Some 77 members of the 2012 rich list were billionaires, two more than the previous record in 2008. Their good fortune contrasted with the economic plight of many Britons who face five years of austerity aimed at wiping out a record budget deficit as the economy struggles to recover from the 2008 financial crisis.

The three top places in the list were taken by foreign-born magnates with a base in Britain who earned their fortunes from resource-based industries such as minerals, steel and oil.

Lakshmi Mittal retained his crown as Britain's richest man despite losing almost a quarter of his wealth over the past year following a fall in the share value of his ArcelorMittal, the world's largest steelmaker. The Indian-born businessman saw his personal worth slide by £4.8bn to £12.7bn, but that was still enough to keep him on top of the list.

Uzbek-born billionaire Alisher Usmanov, who owns around 30% of Arsenal football club, was again in second place and close behind Mittal with a fortune of £12.3bn.

Russian investor Roman Abramovich, who owns rival club Chelsea, held onto third place with a personal value of £9.5bn, down from £10.3bn last year.

The richest British-born billionaire was the Duke of Westminster who slid from fourth to seventh place even though his largely property-based fortune rose 5% to £7.35bn.

Britain's richest woman was former Miss UK Kirsty Bertarelli, who shares a £7.4bn fortune with her Swiss-Italian entrepreneur husband Ernesto.

The annual list is based on identifiable wealth, including land, property and other items such as art, racehorses or significant shares in publicly quoted companies, but does not include bank accounts.

• This article was amended on 30 April 2012. The original said that the richest British-born billionaire was the Duke of Wellington. This has been corrected.