On an earlier website in DNN 4 there were options in Site Settings, Advanced Settings, Other Settings, Default Language for English (United States) and English (United Kingdom)

In my new site in DNN 5 there is only the option for English (United States). I must have dates displayed as dd/mm/yyyy NOT mm/dd/yyyy

How can I get hold of English United Kingdom)?

[Edited by moderator to remove markup]

I seem to have unearthed a can of worms here!
When I open the site in Firefox 3.5.5, at the top right of each page there is now a US flag and a UK flag.
One of my pages displays a monthly calendar with 1/29/10 at the top (today, defaulting to US format).
When I clicked on the UK flag this changed to 29/1/10 - OK.

I then exited FF and tried this in Internet Explorer 7 and when I clicked on the UK flag I got
Critical Error.
Conversion from string "1/29/2010" to type "Date" is not valid.

I exited IE and reloaded in FF and I now get this Critical Error here as well.

(My old DNN 4 site had a drop-down list at top right of the Home page for English (United Kingdom) and English(United States).
This generally defaulted to UK English but I needed to put a message in for users to check that English (United Kingdom) was displayed and what to do if if English(United States) was showing.)

I there any way that I can force my new site to default to English (United Kingdom), or better stiill, remove English (United States) completely?