The answer is “not Tobin”, no matter what this might seem. The Tobin tax is specifically a tax on foreign exchange transactions, originally designed to damp down movements in a notoriously volatile market rather than to raise money. Campaigners for a Financial Transactions Tax(FTT) have sensibly switched attention from said currency tax – which, given the lack of regulation of FX trading, is susceptible to traders simply switching jurisdictions – to levies on bonds and equities sales. Bill Gates, who was asked to look into this issue for the G20, sounds like he will be in favour of something similar, together with eminently sensible ideas such as raising tobacco taxes in developing countries and levies on shipping and airline fuel.

That said, the EU FTT doesn’t look particularly workable – and I’ve even heard rumours it was made deliberately so by sceptical Commission officials trying to sabotage it from within. A tax on transactions in a particular exchange, if it can’t be bypassed, makes perfect sense at least as a money-raising device. The UK, despite its continual whingeing and mewling about an FTT, has taxed British stock transactions through Stamp Duty for a very long time – and added a new version to cope with sales of uncertificated stock. A levy based on the tax residency of the investor looks more difficult to implement, as it is subject to the usual shifting of registration offshore.

In any case, perhaps the Commission should be spending more of its time on putting out the raging house fire that is Greece rather than making minor adjustments to the architecture. It isn’t excessive volatility in financial market trading that is causing the eurozone to go up in flames but boneheaded currency, fiscal and debt policy. First things first.