Two hundred energy traders will gather in a West End hotel on Thursday, courtesy of the New York Mercantile Exchange, “to celebrate the return of open outcry trading to London”. But there may not be too much to celebrate: volumes at the exchange’s London floor have fallen to a trickle since its launch five weeks ago.

By contrast, volumes at its rival for the North Sea Brent contract, the International Petroleum Exchange, have risen by more than a third since April, when it closed its floor and moved to electronic-only trading. More worrying for Nymex is that the Brent volumes are narrowing the gap with Nymex’s benchmark West Texas Intermediate contract.