Boris Johnson's government is "seriously" looking at madcap plans to build a 25-mile bridge to Northern Ireland.
Downing Street insisted today that the £15bn project is not a pipe dream despite it attracting widespread mockery.
Boris Johnson's record is littered with failed projects - from the much smaller 366-metre Garden Bridge, scrapped by London mayor Sadiq Khan in 2017 after costs spiralled, to an island airport in the Thames Estuary that never came close to approval by the Airports Commission.
Yet despite the past failures, leaked documents last year showed officials at the Treasury and the Department for Transport were asked to look at risks and costs of the project.
And the Prime Minister's official spokesman confirmed today: "Work is under way looking into the idea of the bridge."
He added: "The Prime Minister is ambitious in terms of infrastructure projects. He’s looking at a wide range of schemes across the UK that could boost productivity."
It's thought a bridge would run from Portpatrick, near Stranraer in western Scotland, to Larne, near Belfast.
Experts have warned the sea channel between Portpatrick and Larne is almost 1,000ft deep and may contain unexploded WW2 bombs. Critics also warn a bridge could harm shipping across the Irish sea.
Despite support for a bridge from the DUP and some Irish politicians, it is also not known what role, if any, the Scottish would play in building or maintaining the bridge and its approach roads.
Yet asked today if officials were taking the idea "seriously", Mr Johnson's spokesman replied: "Correct."
And a source close to the PM talked up the idea of a bridge - by pointing to longer structures in places like China.
"Greater feats have been achieved elsewhere in the world", they said. "The Prime Minister thinks it's something that's worth looking at."
It's understood the UK government believes there wouldn't need to be customs checks on the bridge.
That is despite the government's own documents previously saying firms would need to fill out customs declarations for goods travelling from Great Britain to Northern Ireland.
EU customs checks and tariffs would then be required on goods "at risk" of entering the EU - for instance, the Republic of Ireland - at a later date.
Mr Johnson personally signalled his support for the project in December, telling a DUP bridge-backer: "All I can say is it is a very interesting idea.
"I advise him to watch this space and indeed watch that space between those islands. What he has said has not fallen on deaf ears.”
But an SNP spokesman said: "It is going to take more than a bridge to undo the harm to EU relations that the Tory government has caused with its extreme Brexit plans.
"And given Boris Johnson’s failed history of unwanted and over budget bridge projects we are going to take a lot of convincing.
“The SNP will always welcome engagement with how we can strengthen relations with Northern Ireland and Ireland, but we will focus on practical and achievable ideas - not unsubstantiated vanity projects and baseless briefings which this Tory Prime Minister is all too familiar."
A UK Chamber of Shipping spokesman also blasted the plan, saying: "We fully support any initiative which seeks to improve trade and tourism links. However, there are already a range of ferry operators taking tourists and trade between Northern Ireland and Scotland.
"Spending £15bn-£20bn of taxpayers’ money on a bridge simply to replicate what those ferries already do is unnecessary. The money could be far better spent improving road and rail links to our ports across the UK.”
