Today I learnt how to access old, archived versions of government websites, including those that no longer exist.
The answer? The UK Government Web Archive, hosted by the National Archives. You can browse by category or choose your organisation from an A-Z list. Once you've selected your organisation, you can choose the date of the archived version of their website you'd like to view and away you go. It's really useful, especially for websites that no longer exist (e.g. Inland Revenue). And, of course, it's free.
UK Government Web Archive:
http://www.nationalarchives.gov.uk/webarchive/
For more information about the National Archive's government website archiving project:
http://www.nationalarchives.gov.uk/webarchive/information.htm