Steve Hilton, David Cameron's closest confidante, is to spend a year teaching at Stanford University in California


Hilton believes he is leaving at the right time with the bulk of the party's 2010 manifesto agenda gradually taking legislative shape. But he has been pondering his departure for many months, expressing frustration at the slowness of the government machine. A natural insurgent, he feels at times he has been banging his head against a benign brick wall of civil service complacency. Although there has been no great rupture, there has also been a gradual disillusionment that Cameron in office has not proved as radical or risk-taking as he hoped. His often impatient style lost him some friends in the civil service, leading to hostile briefings that suggested his ideas were impractical. He himself became frustrated at the pace at which the civil service moves, the apparent deference to EU regulations and the feeling that the levers in Numbers 10 do not work.