Britain is part of Europe (a continent).
Britain is not part of the EU (a supra-national political entity which came into existence in the early to mid 1990s).
Please don't conflate Europe and the EU. It's a fairly common mistake.I'm aware of both of those things. I was referring to the 'splendid isolationism' and strain of Euro-skepticism in Britain, especially after 1815. The wishing to seem to be a major part of Europe without wanting actually to take part that dominated the 19th century. Even in WW1, if the Belgians had made a slightly different choice and chosen to allow the German army passage through their country unopposed on the way to France, it's unlikely Britain would have gotten involved, because there would have been no violation of Belgian neutrality to obligate them.
That's all I meant. Of course Britain is geographically part Europe, but there has historically been ambivalence about how much it wants to involve itself in continental things. The luxury of being an island.