January sales start early to coax customers on 'Panic Saturday'
Millions of shoppers have been out in search of bargains as many retailers started their January sales early.
The Centre for Retail Research predicted 12.6 million people would hit the high streets on what has been dubbed "Panic Saturday", with just six days left until Christmas.
Experts said retailers had been left desperate to shift stock following disappointing Black Friday sales.
Discounts were expected to average 45%, financial advisory firm Deloitte said.
With six days remaining before Christmas Day on Friday, shoppers had been expected to embark on a £6bn spending spree - up 23% compared with the the same period last year, when Christmas Day fell on the Thursday, researchers said.
Jason Gordon, consumer business partner at Deloitte, said: "Compared to 2014, there is already a noticeable increase in both the volume and value of discounts in the run-up to Christmas this year.
"Whilst this is good news for consumers looking to grab a bargain, it is a clear sign that retailers are being faced with what is now an annual uphill battle."
Gary Turnbull, general manager for Intu Braehead in Glasgow, said the shopping centre had been "extremely busy".
He added: "There's still another five shopping days left and I reckon it's only going to get even busier the closer we get to the big day."
The industry did not reap the rewards of Black Friday - a US shopping tradition imported across the Atlantic, where retailers offer discounts the day after American Thanksgiving in November to kickstart the Christmas shopping season.
Experts said this year's UK Black Friday failed to boost sales and many retailers did not make the discounts shoppers had been hoping for.
Meanwhile, it appears so-called "Mad Friday" did not produce a surge in alcohol-related arrests but emergency crews across the UK were certainly kept busy.
Charities and health campaigners had warned revellers to drink responsibly on Friday night, one of the busiest days of the year for UK pubs and clubs.
Chris Wood, from the West Midlands Ambulance Service, spent the night treating people who had over-indulged in Birmingham.
"Last night we saw 20% more workload than last year," he told the BBC.
"Certainly a great deal were drink-related - we saw about 50 patients in Birmingham city centre who were all alcohol-related."
Ch Insp Chris Matthews spoke to the BBC while patrolling Leeds city centre.
"Not overly busy from last Friday, and that's possibly because people are working into Monday Tuesday, Wednesday next week," he said.
"It's a really lively night, a really good-natured night in Leeds. So far we've had maybe 10% more calls in Leeds than we would have done."
Kevin Brown, deputy director of operations at the London Ambulance Service, told BBC Radio 5 live late on Friday night: "We will expect about 5,300 emergency calls each day, here in London.
"What we've seen in the last three hours is over 1,000 999 calls and we've identified in excess of a 100 of those relate to alcohol."
Greater Manchester Police tweeted: "As of 9.30pm, incidents recorded are up 12% on last Friday. Calls are also getting louder, judging by the raised volume in the room #madfriday".