Donald Trump doesn't seem to know what the UK is

"You have different names," said Donald Trump. "You can say 'England', you can say 'UK', you can say 'United Kingdom'".

The puzzle pieces that make up the 'United Kingdom of Great Britain and Northern Ireland' have confused school children everywhere, but not quite so many US presidents.

And certainly not those on the tail-end of their trip to the UK, seemingly unembarrassed to imply they believe that 'England', 'Great Britain' and 'United Kingdom' are interchangeable.

In a sprawling interview aboard Air Force One with the Daily Mail, where it was revealed Trump has a stash of personalised M&M boxes, the president continued to tell Piers Morgan:

You know you have, you have so many different names – Great Britain.

 I always say: 'Which one do you prefer? Great Britain?' You understand what I’m saying?

Morgan pointed out that Great Britain and the UK aren't the same thing, to which Trump replied:

Right, yeah. You know I know, but a lot of people don’t know that.

But you have lots of different names.

Trump appeared to hint at his personal favourite name in an interview he gave to The Sunearlier on in his UK visit:

You don’t hear the word 'England' as much as you should.

I think England is a beautiful name.

In an awkward Twitter moment earlier this week, the White House got similarly confused, suggesting that Scotland wasn't part of the UK.

The now-deleted tweet is probably not due to The White House knowing something about the Scottish independence referendum that we don't.

More: Trump and Obama's meeting with the Queen couldn't have been more different