Passport application. What do I put for "country of birth"?

[MitchT]

I'm filling in the form to get a new passport as mine expires in a few months. The "country of birth" section is very ambiguous. It says "Country of birth (including UK)". What does that mean? Do I have to include UK with whatever else I put, e.g. "England UK", or what? I'm confused!

[MitchT]

I remembered that I helped my ex with hers a year ago and we ended up putting England, and that worked, so that's what I've put on mine.