Treaty talks came to nothing, and the British withdrew their protection, opening the way for Ibn Saud, the king of the Nejd, to conquer Hussein's kingdom of Hijaz in 1924, and launch Wahhabi rule over Saudi Arabia.

ECONOMIST: Britain and the Hashemites

But these are static measures ill-suited to crises, when prices fall so fast that, by the time the protection is activated, it is already too late: the financial equivalent of opening a parachute too close to the ground.

ECONOMIST: When the sea dries up