Silicon Valley is the promised land for cash-strapped politicians. Toss a few seeds in the ground and maybe even in a single political term, multi-billion dollar companies can surge up to the heavens. As technology grows cheaper and more powerful, the pace of innovation quickens. Intel and Apple grew quickly, Google much faster, and now Facebook.

Trying to replicate this is an obvious temptation. Many have tried, from cities and states in America to Silicon Fen outside Cambridge and new technology zones in Dubai and Moscow. London now has “Silicon Roundabout”, sandwiched between the City and a revitalised East End, which is becoming a magnet for tech companies and investment.

Some in the British government might have been tempted to highlight this on Tuesday as Barack Obama visited London. Both he and David Cameron, UK prime minister, have shown a proper admiration for the economic fertility of the Santa Clara Valley, which flourished as the financial system crashed. Their administrations are connected through people like Eric Schmidt, the executive chairman of Google. George Osborne, UK finance minister, recently hired Beth Noveck, the head of Mr Obama’s Open Government Initiative, to do similar work in Britain.