News that Transport for London – the body that controls the capital’s vast transport networks and main roads – has been looking at building an underground ring road has resulted in remarkably little adverse comment.

Although very much at the study stage, the ambitious plan would be for a 22-mile long underground tunnel encircling the centre of the capital.

The tunnel would work as a subterranean ring road and could, say supporters, release large amounts of surface space for new buildings, open spaces and cycle lanes because much of London’s cross-town commercial traffic will have been pushed underground.

Press reports claimed that the scheme could cost as much as £30bn. But Transport for London says that congestion in central London could, by 2031, rise by 60 per cent on today’s levels.