It seems that a fixed link between Portpatrick on Scotland's south-west coast and Larne across the Irish Sea is on Boris Johnson's agenda.
When Boris floated the idea of a bridge linking Northern Ireland with the British mainland in 2018, one engineer ridiculed the concept saying it would be 'about as feasible as building a bridge to the moon'. The Prime Minister, of course, has form for proposing grands projects, such as Boris Island - an airport proposed but never constructed on a man-made site in the Thames estuary - and the Garden Bridge, a doomed folly further up the Thames.
But this innovative 'tube bridge' idea is gaining traction. At least, conceptually. Sir Peter Hendy, chairman of the Union Connectivity Review, a study to identify ways to strengthen transport links across the UK post-Brexit, revealed that he has been 'asked specifically' to look into the idea.
Indeed, he has gone so far as to appoint construction bigwigs Douglas Oakervee, a former chairman of HS2 and Crossrail, and Gordon Masterson, a former vice-president of Jacobs Engineering, to undertake an investigation into the proposed crossing.
The scheme attracting growing support is a tunnel - not a conventional one drilled under the sea floor but a revolutionary £12.3 billion 'submerged floating tube bridge', which would sit 50m below the surface supported by a system of pontoons and anchors. At that depth, its proponents point out, 'the water is very constant and calm' and so bad weather is not an issue.
'There's no doubt that a submerged tunnel link would be feasible,' says Professor Guy Walker, head of the pioneering education department at Edinburgh's Heriot-Watt University, which has produced a 169-page report on the concept, saying that it's the cheapest option by far.
The 'floating tunnel' project was originally the idea of Alan Dunlop, an academic and a fellow of the Royal Incorporation of Architects in Scotland. 'In 2018, I was asked by a newspaper if a physical link between Northern Ireland and Scotland was feasible,' he says. 'I was intrigued by that. It would certainly be financially beneficial to both Scotland and to Northern Ireland. So I set about researching it and drawing up some plans and the whole thing took off.'
The submerged roadway has already been given an official vote of confidence. It is one of the schemes covered by a £20 million feasibility study of infrastructure projects considered worthy of further examination by the Hendy review, which will deliver its findings in the summer.