The world is full of urban centres that are trying to emulate the success of Silicon Valley. Ever heard of Silicon Valley North? No, I don't mean San Francisco. It's a term my home town, Ottawa, Canada, has adopted for itself. It's also been applied to Toronto, Vancouver, Waterloo, Calgary, and Montreal. But the truth is that none of them have a decent claim on the title -- they can't touch the real Silicon Valley in terms of scale, depth of expertise or level of innovation.
There's a big barrier to anyone trying to be the new Silicon Valley and it has nothing to do with corporate tax rates or research incentives. Those are all easy to measure and copy. It's the network effect -- the same one that makes eBay, the QWERTY keyboard and Microsoft Office so hard to displace. The smart people want to go to Silicon Valley because that's where the smart people are. After all, being with other smart people is not only more interesting, but more likely to lead to your own success. It's easy to see in a place like Ottawa, where the cream of the tech community are frequent targets for Silicon Valley head-hunters. They go, not (just) for the money, but to be part of that scene.
So good luck East London, but maybe you should have a plan B, just in case.