By Tadhg Enright, Business Correspondent
As the last full shopping day before Christmas Eve, today is expected to be the busiest day of the year on high streets and in shopping centres.
The British Retail Consortium expects between £4bn and £5bn to be spent throughout this weekend.
Researchers at the credit card company, Visa, have forecast sales to peak this afternoon between 2pm and 3pm.
At Brent Cross Shopping Centre in north London, management think today could be their busiest on record and extra security and traffic staff have been deployed to help customers.
Centre manager Tom Nathan told Sky News: "Everything shows us that when Christmas is on a Tuesday and the schools only broke up yesterday that today is going to be enormous because people haven't had the chance to go and do their full Christmas shop.
"So combine that with buying the turkey - and today is the start of the big turkey run - and today is going to be a huge one I think."
But the Local Government Association said confidence on the high street remained low.
Its annual Christmas survey found that 84% of town centre managers said confidence among shoppers had either not improved or worsened compared with this time last year.
It also suggested that the particularly cold and wet start to the winter could also be taking its toll on the number of shoppers visiting town centres.
Sales at Brent Cross Shopping Centre could be the busiest yet Normally the busiest day of the year is December 23 - the last day before Christmas Eve - but this year that falls on a Sunday when trading hours for bigger shops are restricted by law to just six hours.
Big name retailers including John Lewis, Morrisons and Marks & Spencer failed in a bid to convince the Government to relax the restrictions on Sunday trading tomorrow.
M&S has responded by opening more than 100 of its stores at 12.01am on Christmas Eve morning to help shoppers get their Christmas essentials in time.
An M&S spokesman said: "We know that the days leading up to Christmas are some of the most hectic for our customers.
"Due to Sunday trading rules, we can only open for six hours on one of the busiest days of the year.
"We hope that these early bird hours on Monday will ease the pressure and give busy shoppers a bit more time to pick up Christmas food orders or last minute presents."
Waitrose, part of John Lewis, will also extend Christmas Eve trading hours in two thirds of its supermarkets by opening an hour earlier at 7am and closing an hour later at 6pm.
Sky News visited one of its four regional distribution centres at its head office in Bracknell, Berkshire, and saw staff working to deliver twice the normal volume of food to its stores.
They will be working 24 hours a day between now and 6am on Christmas Eve to ensure Waitrose shelves remain stocked.
But management are disappointed for them and their customers that trading will be curtailed on December 23 which is usually their most important shopping day.
Waitrose supply chain director David Jones told Sky News: "If you can imagine what you'd normally take in trading over 14 hours and shrinking that into six hours, it's quite challenging as you walk around the supermarket.
"You're trying to get people through checkouts and we would have loved to have had the opportunity to trade for a longer time."
Mr Jones will be taking time out from his executive duties to man the tills in his local branch over Christmas.
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