Bargain hunters started queuing early this morning for the Boxing Day sales as experts predicted 22 million people will hit the shops today.
Shoppers eager to grab the best deals snaked round the block outside department stores waiting for them to open.
Crowds braved the wind and rain to queue up outside luxury department store Harrods, while eager shoppers poured through when the doors opened at Selfridges in central London this morning.
Millions are expected to hit the high street today and spend as much as £3.74 billion in the most hotly-anticipated shopping day of the year.
Shoppers endured rain to queue up outside Next in Liverpool City Centre from 4.30am and long queues had started to form by 6am.
While eager bargain hunters flocked to Brent Cross in north London to snap up the deals on offer.
As the shutters went up at River Island in Brent Cross, shoppers surged underneath with many immediately dashing to the discounted handbags.
Brent Cross general manager Tom Nathan said he expects strong sales in luxury goods such as jewellery and watches, which are heavily discounted.
He said: "You get the sense that people are really in for a bargain. Over the last three weeks people have been focusing on buying gifts and this is really 'me time' now.
"People realise there are some great bargains in winter merchandise like coats and boots.
"It could be a record week, but it is too early to say anything other than that."
Figures from VoucherCodes.co.uk and the Centre for Retail Research suggest 22 million shoppers are set to spend £3.74 billion in the Boxing Day sales - a 6% increase on last year.
In good news for the high street, the research predicts that 78% of total Boxing Day transactions will take place in bricks and mortar stores.
But online sales are set to be up 13% on last year.
VoucherCodes managing director Claire Davenport said: "While pre-Christmas sale dates have soared in popularity over the last couple of years, it seems they are yet to take over our more traditional savings days, with many retailers choosing to go all out on Boxing Day, running deals as early as Christmas Day right through to the start of the New Year."
Department stores Harrods, Selfridges, Liberty and House of Fraser are offering designer goods at a fraction of their usual price, while both Next and Marks & Spencer have launched discounts of up to 50% on sale items.
Retailers across London's West End are preparing to take over £100 million in sales over the next three days.
A number of Bond Street stores will open on Boxing Day for the first time as a result of it falling this year on a Saturday rather than a public holiday.
Fenwick department store on Bond Street will open for its first Boxing Day in its 124-year history.
Steve Richardson, UK regional director at analysts FootFall, said: "With Boxing Day falling on a Saturday, this means for most an extended Christmas break with the extra bank holiday on Monday.
"We anticipate the extra day will motivate shoppers to use this additional day off to seek out further bargains, spend Christmas vouchers and even return or exchange unwanted Christmas gifts, causing shopper traffic to rise 3% year-on-year on Boxing Day."
Usdaw general secretary John Hannett urged shoppers to respect store staff "every day, but particularly during the Boxing Day sales when bargain hunting can turn into a frenzy".
Online shoppers are expected to spend £856 million today, up 22% on last year's £699 million, according to data firm Experian and online retailing trade association IMRG.
Steven Madeley, general manager for St David's shopping centre in Cardiff, Wales, said he is expecting thousands of shoppers.