I type this direct from a PC Mag dated Jan 2003 as follows:
There are two possibilities here: the default language and style languages. First, create a new blank document. Got to Tools, Language, Set Language. Select English (UK) from the list then click the Default button. Next, go to Format, Styles and select, in turn, each of the styles you commonly use. You should see a summary of the style on the right, including the proofing language. If this still shows 'English (US)' then click Modify. In the next dialogue click Format, then Language, and select English (UK). Exit Word - if you are asked whether to save changes to Normal.dot, then do so.
Worth a try..Lap..