While the rail and underground system in 2050 will look recognisable to today’s Londoners, if significantly expanded, surface transport will not. Technology is going to change the way we move around to an extent we can barely imagine. It’s not that we will be swooshing around town in driverless pods, taking delivery of our groceries by drones, but pervasive use of digital technology will enable massive shifts in our modes of transport – and very much for the better

In London, as in most cities, around one third of road space is taken up by parked cars, a really daft use of road space (not to mention a vast subsidy for those who happen to own cars). Private cars have had a good century: they have dominated our streets, for good and for bad, but they palpably going out of fashion in cities around the world.

It’s not simply that public transport is improving – remarkably so in London – it is also that owning a car is no longer the key to urban mobility which it used to be. If you need a car, you now summon one on your phone – whether it is a cab, or a minicab. Need to get out of town? That’s what car-clubs are for. Need a van? There’s an app for that. And maybe you don’t need a car at all, because now you have an all-knowing travel-planner in your hand, so you can make sense of all those train and bus routes and timetables. Or perhaps you’ll just walk – because now even tourists can find their way around unerringly, using the maps on their phone. Or jump on a Boris bike (and yes, they will still be called that in 2050).

So what are we going to do with all the parking spaces this revolution will free up? Bus lanes, cycle lanes, filter lanes, pocket parks, cafés, even housing. Or car-club parking spaces: for every 12 people who join a car-sharing scheme, 11 cars are taken off the road.

Of course our streets will still be busy – we’re talking about London after all. But one thing we won’t have is taxis and minicabs circling around looking for their next fares. Even though most of London’s vehicles will be electric by 2050 – they will be cheaper and better than internal combustion vehicles on all dimensions within the next decade – clogging our roads with empty vehicles already makes no sense at all. With or without drivers, taxis and minicabs will be parked up, waiting to jump into action at the click of a button.

Digital management of road space and parking, along with the electrification of almost all vehicles, will have solved London’s current air quality problems by 2050 (though we may be worrying just as much about metallic and plastic dust, rogue nanoparticles or volatile organic compounds by then).

London’s population growth and climate change mean that the super-sewer will be seen for what it is: a costly, over-engineered white elephant, which fails to solve the problem it was meant to eliminate. By 2050 we will have shifted to sustainable drainage approaches to rainfall management.

London will be a sea of green roofs, new roadside and rail-side parks, restored riverscapes and permeable road surfaces. The Green Belt will have survived more or less intact.

By 2050, we will have commissioned a second tidal barrier and enhanced flood protection, to make absolutely sure that London is spared the catastrophic floods that will be increasingly affecting coastal cities around the world.

London will have spread East, and it will be more densely populated. But it will still be the greatest city in the world. It will provide a wonderful environment in which to live and work – and it will have to, because other cities will be competing relentlessly to attract the smartest, most mobile knowledge workers.