Retail white sales in December dropped 1.9% from the previous month, according to lawful figures.
Sales across all main retail sectors declined, with the heaviest capitulates coming at non-food stores, the Office for National Statistics (ONS) said.
It was the biggest monthly be captured for more than four and a half years.
The Black Friday knock offs in late November made it «even harder… to keep shoppers assign during December», analysts at Lloyds said.
Experts had predicted a much smaller 0.1% monthly collapse.
Retailers had a «disastrous December… much worse than calculated,» said Alan Clarke of Scotiabank.
Inflation figures earlier this week showed payments rose more than expected in December, «and now we also know that jumble sales volumes fell», Mr Clarke said.
«This is likely to be the theme for the recline of the year — higher prices will reduce disposable income and sad consumer spending growth,» he added.
Martin Beck, senior financial adviser to the EY Item Club, said «the squeeze on households’ real receipts is gradually tightening, implying a tough 2017 for retailers».
Clothing, footwear and household nobles all saw «particularly sizeable drops» last month, he added.
However, when approximated with a year ago, retail sales were up 4.3% in December.
«There were some distinctly strong figures from smaller retailers, in particular butchers, who examined a significant boost in sales in the run up to Christmas,» said Kate Davies, ONS older statistician.
Shoppers also bought more online, spending anent £1bn a week, which was 21.3% higher than in December 2015.
Despite the inferior December figures, «retailers shouldn’t assume that they determination lead to a bad January as well», said Keith Richardson, managing top banana of retail at Lloyds Bank Commercial Banking.
«Consumer spending remained up — against expectations — after the EU referendum and it may do so again.»
On Monday, Bank of England governor Identification Carney said household spending was still strong after the Brexit express, but warned the UK economy was becoming overly reliant on consumer spending.