Since 1st January 2005 our UK dates have been interpreted as USA dates. 11th January 2005 appears as 1st November 2005 (1/11/05 instead of 11/1/05).
Whether you use Short or Long Dates format the 2004 and 2005 date output will be interpreted differently.
The Solution. I discovered that if you select English (Australian) instead of English (British) then it works as expected. If you use English (American) then the short dates are MM/dd/YY format but the Long Date format will appear always correctly irrespective of the year. ie 29th December 2004 and 3rd January 2004.
As far as us Brits are concerned we will use an Aussie date setting if it gets the result we need.
Stuart