The rise of Jeremy Corbyn could help Britain stay in the European Union. That may seem counter-intuitive: the new leader of the opposition Labour Party is no fan of Brussels. But Corbyn may have a helpful effect on shaping the future decisions of the ruling Conservative government.
There are two ways Corbyn could bring Britain closer to Europe. One is if he resets Labour policy to some of his more racy Left-wing ideas: nuclear disarmament, wholesale nationalisations and a push for an EU exit, based on its perceived interest in capitalists at the expense of workers. The Opposition would probably split, with a big chunk joining the Tories in a beefed-up centrist campaign to stay in Europe that would have a good chance of success.
The other possibility is that Corbyn proves moderate. That could also help the pro-European cause. Properly packaged, some of Corbyn's ideas - de-privatisation of foreign-owned natural monopolies, and infrastructure investment - are more mainstream than Prime Minister David Cameron would like to admit. Cameron only has a small parliamentary majority and his chancellor, George Osborne, has a track record of taking the sting out of Opposition policies like the minimum wage by adopting and adapting them.
Corbyn could affect Tory positioning on Labour issues. He is likely to make a bigger effort to protect workers' rights, which might be weakened under the current government's challenge to pan-European rules. The Conservatives may face pressure to row back on this, and on other thorny issues like migration, in order to neutralise him - making the "In" campaign potentially more moderate and appealing to swing voters.
There is another important battleground: the City. Osborne is attempting to protect financiers from regulatory depredations, while Corbyn's hard-Left stance is likely to leave little room for sympathy where bankers are concerned. But given this drive is really about safeguarding UK powers against Brussels' overreach, there may be common ground here too.
Plenty of things could go wrong - the United Kingdom is entering a period of political instability, and if Corbyn decides to make his support for remaining in Europe contingent on the outcome of Cameron's renegotiations it will increase uncertainty. But the scope for Corbyn's election to hasten the UK's departure from Europe looks limited - and it may do the opposite.