I'm all for investment (though not in London - I'd rather we invest in drawing business out of London, to create a more sustainable and scalable distribution of the UK economy), but that does not change the fact that these upgrades are incredibly resource intensive, not just in terms of money but also skilled staff.

There are many tens of billions of investment in prerequisites such as getting rid of level crossings and properly secure rail and upgrading stations and trains that'd be required before you can even think of upgrading mainline rail to driverless. For the London Underground, it means a rolling program of platform upgrades, signalling upgrades and rolling stock upgrades that'd similarly be in the many billions.

And yes, now would be the right time to finance it, but even if you start now this is just not happening in the next couple of decades, that was my point.

So by all means, it's worth starting to make the pre-requisite improvements, but it won't bring driverless trains on most of these lines anytime soon.