Safari not getting correct culture settings

Hi

I am a web developer.

I need to know what the Safari user's language and culture is: eg 'en-GB' or 'en-AU'

I am using the header parameter:HTTP_ACCEPT_LANGUAGE to get this setting

For Safari, and only for Safari, it always returns 'en-US'

I have changed ALL my computer and browser settings to English-Australia.

I have NO reference anywhere to English-US (except my keyboard).

So how do I change Safari so that it returns the correct language-culture setting ie 'en-AU' ??

regards

GregJF