A month ago, the UK foreign secretary Boris Johnson suggested that a bridge across the English Channel would be a great idea. Now, the French company that runs the Channel Tunnel opened the subject to the UK government, writing to UK Prime Minister Theresa May.

“The idea of a second fixed link is something that we regularly consider in our long-term plans and we would be delighted to engage with your officials to explore the possibility further,” wrote Eurotunnel Chief Executive Jacques Gounon. “As part of the Treaty of Canterbury and the Concession Agreement which established the Channel Tunnel, Eurotunnel has the right to build the next fixed link.”

Even though in the beginning Johnson’s idea of a cross-Channel bridge was dismissed as an economic impossibility and an engineering liability, Eurotunnel seems to be interested in it, even stating they have first rights to build the link.

“Building a huge concrete structure in the middle of the world’s busiest shipping lane might come with some challenges,” said the UK Chamber of Shipping. Firstly, the Channel would have to include a suspension bridge able to accommodate 80m high ships, meaning it would need towers more than 500m high, said Wanda Lewis, Professor of Structural Engineering at the University of Warwick.

A more likely choice seems to be a second tunnel or even a combined bridge and tunnel, as the costs would only be a small fraction of the £120 billion needed for a bridge.

The idea was brought forward by Johnson during a discussion with French president Emmanuel Macron, as a way of binding the UK and France after Brexit. However, the developments on the project need to wait until Westminster and Brussels reach a deal on Brexit.