The Treasury’s stark assessment of the possible costs of a situation where Britain leaves EU free trade deals raises the prospect of a “soft Brexit”.

But what exactly does that mean? And why is Philip Hammond, the Chancellor, taking a position that puts him at odds with some of his Cabinet colleagues?

Both sides agree that the row boils down to a choice between playing safe and aiming for bigger prizes: soft Brexit means sticking with EU trade rules that have familiar benefits and familiar costs.

Stepping outside those rules offers a more uncertain future, but one whose advocates say includes the potential for greater gains in the form of new trade deals with the US and emerging economic giants in Asia and elsewhere.