the server history of census.pro.gov.uk: (from security space via usenet)

Aug 13, 2002  193.195.171.72  Apache/1.3.26 (Unix)
           Jul 10, 2002  193.195.171.72  Apache/1.3.26 (Unix)           
           Feb 7, 2002  194.131.235.33  No contact           
           Jan 7, 2002  194.131.235.33  No contact
           Dec 9, 2001  194.131.235.33  No contact
           Nov 6, 2001  194.131.235.33  Microsoft-IIS/4.0
           Oct 6, 2001  194.131.235.33  Microsoft-IIS/4.0
           Sep 9, 2001  194.131.235.33  Microsoft-IIS/4.0
           Aug 7, 2001  194.131.235.33  Microsoft-IIS/4.0
           Jul 9, 2001  193.113.180.5  Apache/1.3.14 (Unix)

so the census site started off on apache/unix, someone had a great idea to launch the 1901 census site using microsoft’s iis, they spent about 4 months sorting that out, everything went horribly wrong, and now they are back (and working ok apart from occassional “yes we really are still testing” pages) using apache/unix. surprise.