Research has showed that most customers who visited pound stores came from the "working class", but data for 2011 also shows that that one in eight customers came from the A and B socio-economic group of white-collar professionals. The growth of pound stores comes at a time when other retailers are reporting sales drops. Supermarket giant Tesco, Britain's biggest retailer and one which accounts for more than in British shops, shocked investors earlier in the year with its first in over 20 years.The company reported a tiny rise in second quarter sales after 18 months of underlying sales declines. ( Read More : Tesco Launches Strategic Review of US Stores ) Tesco has 6,351 stores and serves more than 20 million customers aweek. On the other hand, Poundland has just 400 stores and serves 4 million customers aweek. It is somewhat ironic, perhaps, that the phrase "Pile them high andsell them cheap" is attributed to Tesco's founder Jack Cohen.