Many well known banks operating in the UK are based in the European Economic Area, which is made up of all EU Member Sates, plus Iceland, Norway and Liechtenstein. These include ING Direct and Icesave.
All EEA banks have to offer a minimum depositor protection of €20,000, but some of those operating in the UK have chosen to ‘top-up’ their protection to an equivalent level to the UK. The list of those that have topped-up is available here.