The far-reaching project sees commuters entering the tunnels via existing tube stations, with Boris bikes available to hire at the entrance.

Its blueprints go further by creating a vision of a vibrant subterranean space filled with artists, pop-up cafes and exhibitions, amid happy crowds of cyclists and walkers.

The plan suggests initially using tunnels between Green Park and Charing Cross Road and between Holborn and Aldwych, in the heart of London, for the project. But it says there are plenty of other spaces that could be adapted too.

It even throws in an eco-friendly element, by proposing the Underline generate its own electricity using kinetic paving from the friction of walkers and passing bikes.

The idea has been commended for its big-sky thinking with an award for Best Conceptual Project at the London Planning Awards this week.

However it is a very long way off landing a green light for planning permission. In fact, news of has already been greeted with cynicism by some commentators, who argue that it is a completely impractical solution to London's congestion problems, because of short tunnel lengths and the non-cycling bridges that connect relevant tube stations.

London Underline project wants to transform disused Tube tunnels into cycle routes