Browsers
Royal Mail decided early on that we were only going to support 95-97% of the browsers commonly used in the UK. We have limited funds and feel that they’re better spent on making the site accessible for disabled users on mainstream browsers. After all, a blind person cannot choose to become seeing but a person who is using an unusual browser can switch.
The list of browsers we support is reviewed at least every six months. To help us make decisions, we monitor our own site as well as general trends in the UK. To take one example, we started supporting Firefox on Windows in early 2006.