When the London Stock Exchange last replaced its chief executive eight years ago, it took four months from the time the incumbent, Gavin Casey, resigned to the moment a replacement, Clara Furse, was appointed.

The search for a replacement for Dame Clara, being handled by City headhunter Anna Mann, has been going for half that time. But with an uncertain year ahead, the scale of challenges for the exchange is so great that the LSE may not want to wait too long before picking a new leader. "It's crunch time for the LSE," says a former LSE executive, now at a European exchange.