Retail sales rebounded far more than expected in January after December's heavy snow, but the true strength of consumer demand after a sales tax rise remained unclear, the national statistics office said last Friday. Retail sales volumes jumped by 1.9% on the month, more than three times faster than analysts had forecast, following December's downwardly revised fall of 1.4%, the worst for any Christmas on record. But economists warned that it was too early to tell how consumers were facing up to a value-added tax rise and public spending cuts this year. The ONS said it was hard to disentangle the effects of two successive rises in VAT in January 2010 and January 2011, combined with unusually harsh winter weather in January 2010 and December 2010. However, there was some anecdotal evidence that shoppers made major purchases before the VAT rise took effect on January 4, and that sales fell off thereafter, a pattern also noted by the British Retail Consortium. Year-on-year, retail sales volumes were up by 5.3% in January, their biggest annual rise since November 2004. But last month's data was flattered by the comparison with sales in January 2010, when harsh weather heavily disrupted trade.