In its annual report, the IMRG says that the past nine years have seen U.K. Internet shoppers spend some £200 billion ($327 billion) online, rising from £8 million ($13 million) in 2000 to an estimated £43.8 billion ($71.6 billion) last year. Annual growth was strongest in financial years 2000, 2001 and 2002. Between April 2008 and April 2009 the Index shows the U.K. e-retail market grew by 14 percent, a record period of low growth.

Both the clothing and the electrical sectors have recorded consistently strong growth since the index launched. The clothing sector has continued to grow rapidly, increasing 1,990 percent since February 2001. This sector consistently outperformed the total e-retail market and all other online sectors in terms of index value throughout 2008 and was the fastest-growing online sector last year.

"When we entered the 21st century, Internet shopping was in its infancy," says Tina Spooner, director of information at IMRG. "Nine years later e-retail has not only become a channel of retail choice for consumers, but a way of life for many. Internet shopping is clearly the bright spot in the U.K. retail sector, but this industry is still young and has great potential for further growth."

Over 100 e-retailers contribute data to the IMRG Capgemini Index, including e-retail specialists and traditional retailers with e-retail operations.