The clown king of novelty infrastructure fantasies has once again stolen the limelight with his preposterous plan for a 22-mile bridge across the Channel. As spending priorities go, Boris Johnson’s idea is madness. Most places outside the south-east UK languish with medieval infrastructure – and there’s also the fact that it’s the busiest shipping lane in the world.

But none of this matters. In a world where Johnson got as far as flushing £37m of public money into the Thames on another fantasy project, the Garden Bridge, a great Channel crossing could easily be conjured into being. No doubt his go-to designer for overpriced public baubles, Thomas Heatherwick, has already rustled up a design.

Could we be in line for another copper-clad fungal confection, sprouting up from the waters with a sprinkle of fairy dust and a streamlined procurement process. Perhaps it will be an ingenious contraption designed to roll back on itself to form a climbable sculpture of Joanna Lumley’s hair.

Or might the lord of self-initiated mega-projects, Norman Foster, already be working on a scheme? He has form in coming up with seductive infrastructural visions for Johnson, having produced a compelling plan for “Boris Island”, a futuristic airport in the Thames Estuary connected by high-speed rail links and depicted in a permanent Blade Runner glow.

That said, Foster’s Millau viaduct in France (designed, in a model of cross-Channel collaboration, with Frenchman Michel Virlogeux) is one of the most elegant long-span structures in the world, a piece of minimalist brilliance that hangs in the valley like a diaphanous spider’s web, giving you the feeling of floating in the clouds. Foster would no doubt concoct something equally refined to span la Manche – perhaps with a thrilling added wobble, like the one his Millennium Bridge had.

Another likely candidate to bring a touch of ageing celebrity sparkle would be the world-renowned (and self-appointed) iconic bridge tsar, Santiago Calatrava. “I tell you, I have been involved in something like 50 projects in very different cities,” he said at a lecture in Dubai in 2016, presenting identikit white whalebone structures – and struggling to remember which cities some of them were in.

For all the lazy stylistic repetition, however, it was hard not to be wowed by his spectacular proposal for Doha Bay. A series of bridges and tunnels that dip and dive out of the water like some writhing sea monster bearing down on the Qatari capital, such a creation could provide a template for getting around all those pesky boats in the Channel. It might take the entire EU annual budget to pay his fees, though.

But for Johnson’s vanity projects, funding is never an obstacle. Having offered Emirates Airlines a permanent place on the London tube map in exchange for their part-funding of the empty cable car link across the Thames, surely he could wangle a similarly great deal for the Boris Bridge? Perhaps his chum Lakshmi Mittal could step in to donate some steel, as he did for the ArcelorMittal Orbit tower in the Olympic Park, another cunning wheeze that resulted in a structure that has cost the taxpayer up to £10,000 a week to maintain.

Or might he look east? Boris’s address book is brimming with Chinese billionaires, including Xu Weiping, to whom he sold east London’s Royal Docks for £1bn, amid claims of a cosy relationship. China has, after all, become the world leader in long-span structures. Seven of the 10 longest bridges in the world are now in the country, from the 102-mile Danyang–Kunshan Grand Bridge in Jiangsu, to the stunning series of cable-stayed bridges and tunnels that will finally connect Hong Kong with Zhuhai and Macau later this year. And if the money runs out, it could always be turned into the world’s longest whiff-whaff table.