Shops, banks and other businesses are turning away six million potential customers because their websites prevent disabled visitors from accessing them fully, according to BCS charity AbilityNet, which advises on IT to support disabled people at work and at home.
"When we look for information, services or goods online we are not seeking a life-changing experience but speed and efficiency," said Robin Christopherson, web consultancy manager at AbilityNet.
"Accessible sites are easier to use for everyone. Research by the Disability Rights Commission shows that able-bodied users find sites designed for access by disabled people are 35% faster and easier to use. Some retailers offering different versions of their sites for disabled and non-disabled people report big demand for the more accessible versions from all types of customers."
Christopherson, who is blind, has led AbilityNet's regular studies of websites of companies ranging from banks to supermarkets and airlines, and the results have been consistently disappointing. The latest survey, of 10 telecoms services, gave Onetel and Kingston Communications four stars out of five - only the second time in eight surveys that any sites have gained four stars.
Indeed, AbilityNet's results support a Disability Rights Commission study of 1,000 UK sites which found 81% failing basic accessibility tests.
Yet meeting the needs of visitors with various impairments can be quite simple, Christopherson said. It boils down largely to thinking about users rather than clever design.
Sites with moving images such as Flash movies can lose potential business from those who cannot use a mouse, have a cognitive problem such as epilepsy, or are visually impaired and use speech output, Christopherson said. He said research shows that web users look at text more than graphics in any case.
Text size on some sites is hard-coded and cannot be easily enlarged. Some sites carry a watermark. Both features largely rule out 1.6 million visually impaired customers.
Visually impaired people depend on speech output to read text labels attached to images, but these labels are often uninformative or absent. "Without these spoken labels on graphical links, navigation for a blind visitor is guesswork," Christopherson said.
Pictures of text are often used instead of text. This means visually impaired or dyslexic users cannot modify the size or contrast, and, again, if the content is not labelled it cannot be read by a screen reader.
Companies cannot afford to continue with inaccessible web design, Christopherson said. "Inaccessible sites exclude a potential UK market of 1.6 million vision impaired users, 1.5 million with cognitive difficulties, 3.4 million with disabilities preventing them from using the standard PC set-up easily, and millions with dyslexia or literacy difficulties, not to mention increasing numbers of elderly users. Their total spending power is estimated at £120bn a year. Companies ignore this market at their peril." Web content accessibility guidelines: www.w3.org