In 2011 retail businesses generated an estimated £21.4 billion from e-commerce sales, up from £15.2bn in 2010, according to the ONS data. Of the £21.4bn, £17.6bn was generated from sales made on retailers' websites.
The remaining retail sector e-commerce sales in 2011 were generated through Electronic Data Interchange (EDI). EDI is the "computer-to-computer exchange of documents in a standard electronic format," according to the ONS.
The ONS said that the total estimated e-commerce sales in the UK last year – calculated by aggregating website sales and sales via EDI – amounted to £483bn, and represented 19% of all sales recorded by UK businesses in 2011. E-commerce sales represented 18% of all sales in 2010, and just 14% in 2008.
The strongest e-commerce sales were recorded in the wholesale and manufacturing sectors, where £181bn and £149bn were generated respectively.
Just 5% of all UK business turnover recorded last year stemmed from website sales, with businesses with 1,000 or more employees accounting for more than half of the £129.1bn website sales. The equivalent figure for 2010 website sales was 4.6%, whilst just 3.8% of all sales revenue was generated through websites in 2008.
More than 81% of all UK businesses had a website in 2011, but just 17% of UK businesses sold through that medium, according to the ONS data. However, 99% of firms with more than 1,000 employees had a website, with nearly half (46%) generating sales through their site.
The ONS said that, for the purposes of the data it had published, an 'e-commerce transaction' was defined as "the sale or purchase of goods or services, conducted over computer networks by methods specifically designed for the purpose of receiving or placing of orders”. It said that the payment and delivery of those goods did not necessarily have to be conducted online in order for a sale to qualify as an e-commerce transaction.