Scottish politicians have to promise to stay in the EU, because otherwise few Scottish voters would say "yes" to independence.
But the "Little Englander" glories in the notion of England being unencumbered by foreign ties and commitments. It's the kind of nationalism that Americans call "isolationism", and the phrase is now used to describe strongly nationalist, even xenophobic people on the right of English politics. Those people, always present in significant numbers within Cameron's Conservative Party, have now won the internal party debate.
Every Conservative leader has had to deal with these people. They always managed to contain them in the past because the European Union is Britain's biggest trading partner, and it is in Britain's interest to belong to the organisation that makes the rules for Europe's "single market". What has changed is that the long recession and relatively high immigration of recent years have increased the popularity of the extreme right in England.
That doesn't mean that populist demagogues and neo-fascists are about to win power in the UK. Far from it: they'd be lucky to get 10 per cent of the vote. But it does mean the Conservatives are losing their more right-wing supporters to the anti-EU, anti-immigration United Kingdom Independence Party.
UKIP could never win an election in Britain, but it could easily steal enough votes from the Conservatives to make them lose the next election. So there has been mounting panic in the Conservative Party, and not just among its instinctively anti-EU members.
Cameron's promise of a referendum on EU membership is an attempt to steal UKIP's thunder and win back the defecting Conservative voters. He doesn't really want to leave the EU, but he really does want to win the election in 2015.
His reluctance to be the man who took Britain out of the EU was evident in the way he hedged around his referendum promise. The referendum would not take place until after the next election, and only if the Conservative Party won enough seats in 2015 to form a government on its own. (Its coalition partner, the Liberal Democratic Party, opposes the idea).
Cameron says he will spend the next two years renegotiating the terms of Britain's EU membership to "repatriate" many powers from Brussels to London, and to make various changes in the way the EU is run. Then, if he is satisfied with the outcome, he will support EU membership in the election and in the subsequent referendum, which will be held by 2017.
But what if the 26 other EU members choose not to waste months in talks on changing Britain's relationship with the EU?
What if they do negotiate but refuse to tie themselves up in knots just to ease Cameron's local political problems? Would he support continued EU membership in the promised referendum if he didn't have a "new deal" to offer the voters? He simply wouldn't answer those questions.
There is much that could be done to improve the accountability and efficiency of the EU, but it is not helpful to open a negotiation with 26 other governments by standing at the exit door and threatening to leave if you do not get your way.
So for the next four years, all those foreign companies that have been using the UK as a convenient, English-speaking centre to produce goods and services for the European market will be rethinking their investment strategies. If the UK may leave the EU by 2017, is this really the right place to put their money? It will probably be a long dry season for the British economy.
How did an allegedly grown-up country talk itself into this position? It's an attitude that was summed up in an apocryphal English newspaper headline of the 1930s: "Fog in [the English] Channel; Continent Cut Off."
Gwynne Dyer is an independent journalist whose articles are published in 45 countries.
