Britain, Great Britain, the United Kingdom (UK for short), England, the British Isles — these different names are sometimes used to mean the same thing, and they are frequently used wrongly. Strictly speaking, England, Great Britain and the British Isles ought to be used as geographical names, since England is only a part of Great Britain. Great Britain does not include Northern Ireland, but the British Isles include Great Britain and the whole of Ireland, that is both Northern Ireland and the Republic of Eire.
They sometimes say that it is as difficult to find a typical Englishman as it is to find a typical Briton. What is the mixture that we call British?