[toldyou]

“In case the president is unaware, England forms part of Great Britain, which also includes Scotland and Wales, though not Northern Ireland, which is part of the United Kingdom.”

[Genoa]

It's sort of tricky, and people sometimes blur the distinctions in everyday speech. For example, the Isle of Man is part of the United Kingdom, but technically it's not part of Great Britain, which properly speaking is a geographical term designating the main island. But to make a long story short, there's no excuse for the Manchild calling the whole country "England."