The volume of retail sales over the Christmas period fell 1% from November, according to the Office for National Statistics (ONS).
The ONS said clothing and footwear sales dropped 6.2% compared with November as a result of unsually mild weather in the run-up to Christmas - however, compared with December last year, sales were up 2.6%.
And it wasn't just the volume of sales where retailers were hit hard. The figures showed that prices were down 3.2% from last year as retailers battled each other to secure sales. The total amount spent during December fell 1.4% on November's total, but rose 1% compared with December last year.
There was also a surprise fall in the value of online sales, which dropped 5.2% from November, but rose 8.2% over the year.
"The fall in retail sales in December was disappointing, and although annual growth in sales at 2.6% is still reasonably healthy, it is still a marked slowdown compared with previous months," said David Kern, chief economist at the British Chambers of Commerce.