There is no "Queen & Country" team listed on Comic Vine, so as far as I can tell, the name is not being used in comics. Therefore, it's viable as an Open Source Team.
Just for the sake of notation, there was a volume:
The phrase is common though, so it's completely reasonable to assume that multiple creators might come up with different ideas based on the phrase, independent of each other.
About "The Paragraph":
Note: Many Open Source Characters (Objects, Teams, etc.) have a requirement that is generally known as "The Paragraph." Basically: its purpose is to keep everyone honest that these new concepts are in the Public Domain. It requires you to include The Paragraph anywhere you use them, letting people know who created the OSC, and that it is available for all to use. I've used my own, modified version of The Paragraph for these blogs to (hopefully) make it clearer what is available, and what is not.
I do this whether the original OSC post requires it or not, because I think it is important for everyone, especially if you are integrating Open Source properties with your original properties, to differentiate between the two. My theory being the clearer you make it, the less legal hassle there will be as time goes on.
cbishop's comments