English to Italian Law/Patents Government / Politics English request of citizenship

I don't think in Crown is about the Royal Family... because the text is about an application for British citizenship. So...who are people in Crown? = militari? ambasciatori? o altro?
Thanks a lot!

"If you are outside the United Kingdom, you will have to return to the United Kingdom to take the test. In exceptional circumstances, it may be possible for a person in Crown or designated service outside the United Kingdom, or the spouse or civil partner of someone in Crown or designated service outside the United Kingdom, to take the test overseas."