SO LET me give you some unadulterated good news about the British economy. It is a story of enterprise and dynamism and young thrusters making their dreams come true. I am talking about a cutting-edge sector that is already employing tens of thousands of people and has scope to take on any young kid who likes fiddling with an iPhone, regardless of academic qualifications - and we have quite a few of them.
Yes, folks, we are looking at the world of apps, those lovely little icons you can activate by just brushing the lustrous stay-clean screen of your gizmo so that you can spend the rest of the day in a happy melon-slicing narcosis.
London is at the absolute shiny needle-tip of global progress, as I can testify, because I have just been around the city's new Wayra academy. It is a special hub, an incubator for start-ups, and it is like a throbbing nuclear pile of competitive talent. It is positively Californian in its youth, energy, brightly coloured beanbags and breakout romper rooms with very good coffee. They are coming up with apps that help you unleash your artistic urges; apps for establishing the sexual preferences of everyone in the vicinity; apps for helping blind people cross the road.
One team had come up with a way of monitoring the language of the entire output of Twitter and other social networks, so they could tell where people were generally happy and where they were generally angry. (They seemed to be pretty cheesed off in Islington that morning, but cheerful in Chelsea).
As we talked my mind raced, and I tried to show that I could invent some apps of my own. How about Pol-u-swerve, so that you can stay in the bath if a canvassing politician rings your bell? Or Fixme, a way of fixing ''Libor'' with no incriminating emails? Or Youhack, so that you can tell at a glance which media organisation is invading your privacy? They looked at me pityingly, but I feel sure that we are now seeing such an amazing collision of technology - search engines, voice analysis, geo-location, face and word recognition - that the possibilities seem boundless.
One day soon I bet there will be something called Howler, an app that allows your phone to parse every word a politician says - and bleep as soon as he or she is guilty of some inadvertent inaccuracy.
This sector is growing so fast that the industry already employs 48,000 people in London, the most in any city this side of the Atlantic, and one day soon someone is going to come up with the next Facebook. We have the brains, we have the restaurants, we have the bars, we have the critical mass of talent. All someone needs is the right idea and then … well, they will need someone to back it.
You remember the decisive scene in The Social Network, the excellent film about Facebook. It is when he goes to the bankers and outlines his scheme. You bet, says the money man. Half a million dollars? No problemo. That is one reason why America has Facebook, Google and Amazon, and that is why - if it is to compete - Britain needs a confident and dynamic banking sector.
It is time for politicians to say it loud and clear and in unison: we need bankers, my friends! We need bankers who are not just cautious, owlish Polonius figures. We need bankers who are willing to take punts and put their necks on the line. Yes, by all means arrest anyone who has been involved in a criminal conspiracy to fix Libor. Bang 'em up. Slam 'em away. But we need the political establishment to stop slagging off a sector that is utterly crucial to the economy and the current system of global capitalism - and after four years of navel-gazing since the crash, we have yet to come up with an alternative.
We need to maintain or lengthen London's lead as the best place to raise and allocate that capital, and we won't succeed in that objective if we keep on bullying, berating and generally beating up anyone who has anything to do with a bank. It's no use regulating them to the point where they are too nervous to lend, and it's no use saying we should get rid of ''casino'' investment banking and stick to good old high street stuff. You need both. You need the high rollers as well as the nice chaps who used to give you sherry.
It is because Britain is so well placed - with the right time zone, language and legal system - to provide financial services that the sector employs hundreds of thousands of people, not all of whom are on stonking bonuses; indeed, most of them are on middling incomes. Collectively they produce tens of billions of pounds that goes on schools, hospitals, welfare and roads. And then there is sponsorship of all kinds. Talk to the people who run London's museums, orchestras and galleries. Do they think we should be continuing this onslaught on the banks? Of course not.
Someone the other day suggested it might be embarrassing to have Barclays pay £50 million to help fund cycling in London. Listen, buster, I said, if they give us another £50 million I will change my name to Barclays Johnson. Of course we should be seeking to rebalance the economy, by building up manufacturing, hi-tech, medical sciences and other areas in which the British show protean powers of self-reinvention. Maybe one day the apps business will employ as many people as financial services; but that day is still some way off, and it will never come unless we have a strong banking sector with imaginative people who are willing to take risks. It's time to stop knocking them.
Boris Johnson is mayor of London.
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