This columnist, as you'd expect from a stiff-upper-lipped Brit of a certain age, is the product of an old-fashioned, boys-only school, which means he only knows this sort of thing by hearsay. But it seems U.K. Prime Minister David Cameron is like the new girl in school.

She hangs around the outside of her chosen clique longing to be let in, using the same color lipstick, wearing the same clothes -- but spoils her chances by lecturing the insiders on their failings. (Odd, really, to think of him that way. The man's from an even more old-fashioned, much more upper-crust boys' school than ours. He is portrayed in cartoons in The Times as the school bully, forcing his junior coalition partner Nick Clegg to polish his boots. But on Europe, at least, the girly comparison holds.)

In much the same way, Cameron wags his finger and hands out lessons on how euro-zone countries should manage their economies. Who can blame French President Nicolas Sarkozy for telling Cameron recently he had "lost a good opportunity to shut up"? Especially since (oh the irony!) the priggish Conservative was only continuing where his self-righteous, much-ridiculed, Labour predecessor Gordon Brown had left off. Both men say they hate the euro, yet both have infuriated the notoriously impatient Sarkozy by demanding a say in the governance of the euro zone. Cameron knows he is regularly outmaneuvered on matters of vital importance to Britain and especially London's vast finance sector, because the U.K. has shut itself out of the inner sanctums of euro-zone decision making. Despite its massive indebtedness and crippling bank bailouts, Britain has survived the financial crisis in much better shape than euro-zone nations such as Ireland or Greece because it has retained its own currency, its own central bank and the freedom to run its economy independently.

But as the euro zone builds defenses and institutions designed for its own needs, Britain has no sway over many of the decisions that deeply affect its economy. It is regularly outvoted on those matters where it does have some say, but has different needs and priorities from its Continental neighbors. It could soon find itself fighting a so-called Tobin tax on financial transactions, which might be more costly to the U.K.'s financial services industry than to the rest of Europe put together.

Cameron and his finance minister, Chancellor of the Exchequer George Osborne, have both understood that the euro zone can only survive with some form of common economic governance, unfortunately at the expense of some fiscal and budgetary sovereignty among its member nations. Yet they rightly fear such a system could encroach on Britain's own freedom of maneuver and sovereignty, while simultaneously putting the country, as a competitor from outside the zone, at a distinct disadvantage.

Now Cameron has an even bigger problem at home. He has courted the ­"Euroskeptic" faction, at the Tea Party end of his own party, with promises to bring back power from Brussels, hold a referendum before acceding to any changes in European Union treaties and above all avoid bailing out struggling euro-zone countries with British taxpayer money.

Yet he finds himself unable to deliver. He has already been forced to help bail out Ireland, the near neighbor that less than a century ago was still an oppressed British colony. Now he is ready to sign up to a much enlarged International Monetary Fund, with a British contribution that could go as high as £39 billion ($63 billion). As one of the founding members of the IMF (and one which would be very reluctant to cede more power and voting rights to a resurgent China or Saudi Arabia, for instance, simply because they have the money to take over the show), Britain finds itself almost duty-bound to stump up unaffordable sums to keep its position on the board.

The IMF needs the extra firepower as it turns its attention from the needs of the poor to the needs of the heavily indebted wealthy: the feckless Greeks, Italians and Spanish whom Britain claims are the responsibility of the euro zone alone. Critics sometimes forget that Britain itself was forced to turn to the IMF in 1976 as the economy declined in a post-imperial world where it could no longer sell high-priced goods to captive colonial markets. The country is in no position to take the moral high ground.

Britain is also, as Cameron himself has been forced to remind his party, deeply dependent on a healthy euro zone for its own economic well-being. Yet even while the zone is threatening to implode, Cameron has been forced to face down a rebellion in his own party ranks. Radical Euroskeptics have been demanding a referendum on withdrawal from the EU.

The prime minister won the day, in the end, only with support from other parties. But his chances of acceptance among the popular girls at school -- if you want to sit at the table of head girl Angela Merkel, you want your loyalty on display at all times -- have been seriously undermined.