There will be a ‘great swollen, throbbing, umbilicus of trade’ between the UK and EU, claims Johnson

Mr Johnson last month raised the prospect of a second crossing to link the UK to mainland Europe following a top-level summit attended by Theresa May and French president Emmanuel Macron.

Speaking in the Commons today, he claimed it was agreed a “committee of wise people” would be established to look at reviving the “great tradition” of UK-France collaboration in matters including defence, space and “infrastructure projects such as the idea of a new connection between our two countries”.

Mr Johnson said the idea was “warmly welcomed” by Mr Macron.

SNP MP Patrick Grady (Glasgow North) raised warnings that Channel ports face “gridlock” if a Brexit transition arrangement was not “urgently” put in place, adding: “What is the point of a 20-mile bridge if there’s going to be a 20-mile queue waiting to get on to it?”

Mr Johnson replied: “I think most people will appreciate that the existing Channel Tunnel is likely at the present rate to be full within the next seven years. That’s a very short time in the lifetime of a great infrastructure project.

“It is a curiosity that two of the most powerful economies in the world, separated by barely 21 miles of water, are connected by only one railway line, and I think it’s a matter for legitimate reflection by our two countries on the way forward.”

Tory MP Richard Graham (Gloucester) widened the issue to insist it appeared as if there would be be a “unique and specific agreement” over Brexit, which would benefit both sides of the Channel.

He asked Mr Johnson if he agreed this should be the outcome of the talks soon to start, with Speaker John Bercow intervening to remind him the question was on a fixed link rather than Brexit.

Mr Johnson replied: “I think [Mr Graham] has hit on the notion of a metaphorical fixed link – a great swollen, throbbing, umbilicus of trade between us – I won’t say which way it’s going – each side mutually nourishing the other.

“I very much approve of the note of optimism that he strikes.”

Liberal Democrat deputy leader Jo Swinson warned Mr Johnson against “indulging in fantasy engineering projects” and suggested his focus should be on “building metaphorical bridges with nations that share our values”, such as France.

She said strengthening ties with European neighbours would prevent “Brexit Britain becoming isolated and increasingly reliant for trade and influence on regimes who have dubious human rights records”.

Conservative former minister James Duddridge said French and English officials were initially mocked when they started talking about the Channel Tunnel, adding: “Can we have more visionary and less mockery about ideas of how we can take forward future relationships?”

Mr Johnson later said the ambition would be for the Channel bridge to be “entirely privately financed” amid questions from Labour over funding.

Shadow Foreign Office minister Khalid Mahmood said: “It’s estimated that we could build the foreign secretary’s Channel bridge at a cost of £120bn. He wants to build bridges at the same time he is pushing for a hard Brexit which will push us away from the European Union.

“Or instead does he think that money could be well spent for the next six-and-a-half years to give the National Health Service £350m per week?”

Mr Johnson replied: “When the first Channel Tunnel was commissioned it was the vision of the then prime minister Margaret Thatcher that it should be entirely privately financed and there is no reason why we should not have the same ambition this time.”

On his widely-debunked “Brexit dividend”, Mr Johnson went on: “As the prime minister herself has said, there will unquestionably be substantial sums of money available to spend in this country on the priorities of the British people – including the NHS.”

Mr Johnson also praised civil servants amid questions from the SNP, telling the Commons: “I have nothing but admiration for the hard work and dedication of Whitehall civil servants who are preparing the Brexit negotiations – and believe me, they are doing a superb job.”