Aldi and Lidl received a boost as stunning new market share data showed half of UK households shopped in the pair in the last 12 weeks. Retail Week takes a look at whether the numbers stack up.

Straw poll – did you shop at Aldi or Lidl in the 12 weeks to December 8?

Chances are, if you didn’t, the person at the next desk did. Kantar Worldpanel data released today showed 50.1% of all British households stepped into one of the two German discounters in the period compared with 46.1% a year ago.

The figures are the latest in a number of swashbuckling stats this year. In the summer Lidl hit a record market share of 3.1% and has maintained it since, it also enjoyed 15.5% sales growth in the 12 weeks.

Aldi, which has about 480 stores, has overshadowed its archrival Lidl, which has 600 shops, by hitting a record 4% market share and recording 30.7% sales growth. It has also opened up on the communications front, revealing in October that operating profits rocketed 450% to £103m as turnover rose 29% to £2.7bn last year.

But how close to reality are Kantar Worldpanel’s numbers?

The stats are calculated using a sample of 30,000 households. The shoppers scan the barcodes of their products after shopping and also send their till roll slips to Kantar. The data covers food, non-food and online across the major multiples and independents and is scaled up to be representative of the 28.5 million households in the UK.

The Kantar data showed that over four weeks, households shop at 3.3 different stores on average and visit stores 4.5 times a week. The figures also show 90% of households shopped at Tesco in the 12-week period while around 60% visited Asda and Sainsbury’s.

But of course, as with all data sets, Kantar has drawn its conclusions by scaling up its findings from a sample, which will beg the question; how truly representative is the 50.1% households figure?

Kantar director Chris Longbottom defended the methodology, saying Kantar uses a “massive” sample, and its findings prove to closely match official sales data from the supermarkets.

Longbottom says the majority of Aldi and Lidl’s custom remains top-up shoppers who also spend at rivals.

“There’s no doubt many are secondary shops but a lot are at the start of the week and if you put a few more items in your basket there, we can see customers are putting a few less in on the main shop at the major supermarkets,” Longbottom told Retail Week.

Moreover, Aldi in particular has expanded its offer this year and Verdict research in October showed a third of new shoppers have been lured from rivals this year, the bulk of which were from the big four.

Lidl, meanwhile, has worked hard to drive its sourcing credentials this year and highlighted that it majors on British meat in the wake of the horse meat scandal.

Iceland founder Malcolm Walker told Retail Week this week that the discounters were directly impacting a difficult month at the frozen food specialist.

Aldi and Lidl’s growth may be astonishing but all the data indicates their dominance shows no sign of abating, largely at the expense of the big four.

They may still represent just 7.1% of the market but who knows what that figure could grow to in the coming years.