Mail Merging Dates Excel to Word Month and day wrong way.

OK. Please read this carefully before replying as I know how to mail merge dates but for some reason its not working properly.

On a spreadsheet I have a list of dates that mail merge to Word 2010, in order to invite people for interview. The dates merge as dates BUT seem to mess up.

ie: if its bringing across from excel 24/12/2011 (so 24 December 2011) it works fine as the date doesnt work any other way round. So Word shows "24 December 2011" HOWEVER....
If its bringing across 12/11/2011 (so 12 November 2011), Word will display it as "11 December 2011." So it works for some dates, but then flips others as if the dates are American.

In excel the cells are formatted to dates in format 14/03/2001 (as it shows in the options) with Locale as English UK.

In word i have MERGEFIELD "Int_Date" \@ "DD MMMM YYYY"

I have no idea what's wrong. I have other spreadsheets that bring the information across fine, but it seems to be just this one. Is there any option anywhere ive missed or anything else?? I've tried using different computers... older versions of Office but it makes no difference. I cant not use this spreadsheet as it has thousands of records.