Millions of bargain hunters have descended on the high street for the Boxing Day sales - with wealthy Chinese tourists helping to fuel record takings at shops.
Crowds started queuing from 1am on Saturday as they braved the wind and rain to get their hands on the best deals.
Experts predicted that 22 million people will hit the stores, spending as much as £3.74 billion.
Selfridges had its most successful-ever first hour of trade, taking more than £2 million between 9am and 10am.
There were nearly 4,000 people snaking around the department store when it opened its doors at 9am, Selfridges said.
Jace Tyrrell, chief executive of New West End Company, which represents 600 retailers in Bond Street, Regent Street and Oxford Street, said wealthy foreign tourists were fuelling bumper sales.
He told the Press Association: "We are in the west end, which is a huge international draw, so we see a lot of international shoppers here - 50% of our shoppers are tourists, particularly from China, the Middle East and the US, and they probably spend about four or five times the amount of a UK shopper."
He said some shoppers had brought along suitcases to stuff with bargains and they were expecting £100 million to go through the tills over the next three days.
He said: "£100 million is the target and we are in line to do that as forecast.
"We are seeing more Chinese here than ever before, which is good news for our retailers, and they are spending a healthy amount of money, which is good for our stores."
Mr Tyrrell said shopping habits have changed, with increasing numbers of savvy consumers going online to find the best deal.
But he said that at Christmas time many still want to see the lights and experience the "touch and feel shopping" of the high street.
Selfridges expects more than 130,000 customers to come streaming through its flagship store and said it is on course to break sales records across its four stores and online.
The first bargain-hunters through the door headed straight for the luxury fashion section. The first product sold in London was a Valentino Wristlet, reduced from £1,400 to £700, the second was an Erdem coat, slashed from £1,695 to £695 and the third was a Victoria Beckham sleeveless dress, reduced from £1,175 to £590.
The store reported massive growth online, with more than one million visitors on Christmas Day and Boxing Day so far. Christmas Day online purchases have doubled compared to last year, Selfridges said.
At its Manchester outlet, shoppers began queuing from 3am and the first buy was a Black Yves Saint Laurent clutch bag reduced to £619.
Harrods in Knightsbridge saw one of its biggest-ever queues, which ran around the corner of the store. The department store expects more than one million customers to come through its doors during the four-week winter sale.
John Lewis launched its sale online, although its shops remained closed, and officials said its sale has got off to a "strong start" after launching on Christmas Eve at 5pm.
In its first hour of online trading sales were up 17.7% on last year, with the Apple sports watch, goose down pillows and a KitchenAid mixer among its most popular sellers.
Shoppers endured rain to queue up outside Next in Liverpool City Centre from 4.30am while Brent Cross shopping centre in north London said they could see a record week of sales.
Long queues and heavy traffic hit the designer outlet store in Bicester Village, Oxfordshire.
More than 20,000 shoppers descended upon Meadowhall shopping centre in Sheffield, where some queued from 2am to get their hands on a discount.
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.