Boxing Day was on a Saturday, which helped sales
Boxing Day sales attracted the highest number of shoppers since records began, according to retail analysts.
Up to 12 million people are thought to have been out looking for bargains some 24 hours after Christmas Day.
The total number of shoppers had risen by nearly 20% compared to Boxing Day in 2008, said Experian.
The rise is thought to be due to bargain hunting before the VAT rate returns to 17.5% on 1 January and the fact Boxing Day fell on a weekend.
The BBC's Nick Cosgrove said: "The rush to the shops over the weekend has been remarkable."
However, High Streets are braced for further tough times in 2010, according to a survey by the British Retail Consortium (BRC).
The BRC said four out of five retailers who responded to its survey said they expected sales would not improve on 2009 levels, dashing hopes of a consumer-led economic recovery.
Chancellor Alistair Darling announced VAT would be cut to 15% in his pre-Budget report last year in a bid to encourage consumers to spend more and boost the economy.
The sales tax rise is set to have the biggest effect on sales of expensive items such as furniture and so-called white goods, such as fridges and washing machines, as people seek the best bargains.
A spokesman for consultancy firm Planet Retail said: "The cold weather just before Christmas meant people weren't spending money as much.
"People on variable mortgages are still quite cash rich and now are thinking 'we want to take advantage of this before the VAT spike', particularly on big ticket items such as televisions and white goods."