[mattkirman]

In this Foreign Office memo [1] from April 2006 "Firecrest is the FCO's IT infrastructure; it sits on the desks of our staff around the world. Firecrest is a globally-networked desktop system that provides users with a standard suite of Microsoft office products including Outlook email, web browsing, Access databases and Excel spreadsheets. Firecrest was developed in 1997 and in 2003 the FCO completed the roll out of the current generation of the system."

Whilst the timing is slightly out (Vista wasn't released to the public until 2007?) it may be possible that Microsoft provided them with a version forked from a much earlier build.

However, the memo does go on to say that the Government were planning a third generation of Firecrest due to be rolled out autumn 2006 with support from HP. This might be the version that is forked from Vista?

[1] http://www.publications.parliament.uk/pa/cm200506/cmselect/c...