If the Tobin tax remains a roving solution in search of a problem, it has at least found a welcoming place to nestle. Taxes on financial transactions, long relegated to the rallies of anti-globalisation activists, now have the backing of the European Commission and of two of Europe’s most powerful governments: Germany and France.

It is sometimes claimed that a Tobin tax might be desirable if it were feasible, but that it can never work. The reality is the opposite. It could be put in place if enough governments really wanted to, but this would be a bad idea.

Transaction taxes are neither as self-defeating as some opponents claim nor as straightforward to put in place as proponents think. Many point to the UK stamp duty on share transactions as proof that Tobin taxes are feasible. But stock trading in the City of London has a centuries-old first-mover advantage and a largely captive market for sterling equity financing. Both discourage avoidance. Other transactions are more footloose. Trading venues for entirely new products may well take transaction taxes into account when deciding where to set up shop.