A rush to the shops to snap up bargains in the last days before Christmas provided shops and stores with one of their best trading months of 2011 in December, the British Retail Consortium said on Tuesday.

Despite the collapse of lingerie chain La Senza and a low-key performance by supermarket group Morrisons, the BRC said deep discounting meant sales in December were 4.1% higher than in the same month of 2010.

Stephen Robertson, the lobby group's director general, said: "A better than hoped-for December closed a relentlessly tough year for retailers, but these figures hinged on a dazzling last pre-Christmas week and were boosted by some major one-off factors. We're not witnessing any fundamental change in customers' circumstances.

"The comparison is with severe snow disruption a year ago. Discounting was deeper and started earlier and the vital Saturday Christmas Eve added another big trading day to the final runup. Post-Christmas offers brought large numbers of shoppers out but that was generally a shortlived hunt for bargains.

"With discounting driving sales at the expense of margins the key question for retailers is about earnings from those sales."

The BRC's monthly snapshot of retail activity showed that once allowance had been made for the opening of new stores during 2011, so-called like-for-like sales were 2.2% higher last month than in December 2010. Excluding distortions caused by the timing of Easter, both total and like-for-like sales growth in December was the strongest since January 2011.

Sales of food picked up in December while cut-price offers boosted non-food spending. Consumers waited until the last minute to do their online shopping, with internet sales showing an 18.5% year-on-year increase last month.

The supermarket group Wm Morrison on Monday blamed its own disappointing Christmas performance on an austerity drive by Britons who bought fewer treats and cheaper food and drink for the festivities.

Dalton Philips, the chief executive, said it had proved tough for retailers to persuade cautious consumers to part with their cash.

"People were making tough choices this Christmas and trading [down] out of certain products," said Philips. He said customers were buying less and had waited until the last minute to stock up on Christmas fare such as mince pies and tins of Quality Street as they stuck to tight budgets.

Like-for-like sales at the Bradford-based retailer grew by only 0.7% excluding fuel in the six weeks to 1 January, falling short of City expectations of about 1.3%. The figure represented a slowdown from the 2.4% rise in the previous quarter.

Once inflation is taken into account, analysts said the retailer's sales volumes must have declined during the important trading period. Although Morrions attracted an extra 800,000 customers a week over the holiday period, Philips said baskets were getting smaller, with shoppers buying "one less item".

"In the mass market, which is UK Inc, people are getting squeezed and buying less," he said. Champagne sales volumes were down 7% but sparkling wine up 156%, with cheaper alternatives to turkey such as pork also in demand. Sales in the week of Christmas were 25% higher than two years ago with more than 40% of products on sale at cut prices.

"It's very aggressive out there," said Philips. He batted away the unfavourable comparison with Morrisons' upmarket rival Waitrose, which last week reported an increase in like-for-like sales of 3.8% for December, implying that its well-heeled shoppers were insulated from the economic downturn than the Morrisons demographic, seen as the "most average" of the major supermarkets. "We have become slightly accustomed to Morrisons leading the way in like-for-like sales terms, with Sainsbury's behind and Asda and Tesco bringing up the rear," said Pritchard. "This Christmas has seen a shift."

Given Waitrose's success – and what is expected to be a strong performance from Marks & Spencer's food businesson Tuesday – he added: "It seems that a combination of an upmarket offer with some web exposure and strong advertising has been the key to 'winning' Christmas 2011. We suspect that Morrisons' campaign came across as rather uninspiring."

Meanwhile, the Kuwaiti-based retail group Alshaya said that it had bought 60 of La Senza's stores, saving 1,100 jobs. A further 84 stores and 16 concessions will close with the loss of 1,300 jobs.

Richard Fleming, joint administrator and UK head of restructuring at KPMG, said: "We are delighted that we have been able to rescue part of La Senza UK and such a large number of jobs, given the negative economic pressures faced by retailers in the UK.

"Alshaya is a leading international retail operator with longstanding links with the UK as the international franchise partner of a string of high street brands. This deal recognises the value of La Senza as a strong and popular high street brand with a loyal customer base."