There was more bad news for online merchants today as a new report by web usability consultancy Webcredible found that half of the UK's leading high street retailers surveyed fared worse in terms of their web sites' customer experience compared to last year.

The firm surveyed twenty of the biggest brands on the high street including Waterstones and Debenhams, marking each out of five in twenty pre-defined areas such as displaying search functions clearly in the same place on each page.

Marks and Spencer was the biggest loser, dropping from a score of 81 out of 100 in last year's survey to just 55, while John Lewis dropped nine points from 71 to 62. The best performing retailers this time around were HMV, which came top with a score of 70, while Game climbed from 18th place to 2nd with a score of 66.

Common areas where firms' sites were found wanting included failing to give the user the option to change the number of products displayed on a page, and failing to change the colour of previously visited links, according to Webcredible's managing director Trenton Moss.

"About two-thirds of the firms surveyed had given their sites a radical overhaul since last year – they've redesigned the front end but they don't seem to have the time energy or motivation to implement key usability features," he explained.