Sir Richard Dearlove, former head of MI6, said only revolution could bring change in Russia (Stefan Rousseau/PA) — © Stefan Rousseau Britain has lost self-confidence without the “essential threat” of the Cold War, a former head of MI6 has said. Sir Richard Dearlove said Britain no longer had the “cohesion and motivation” that drove the former spy when he joined the service in 1966. He told the National Conservatism conference in Westminster: “It never occurred to me that I was not on the side of the angels.” Sir Richard, who led MI6 between 1999 and 2004, said: “Looking back, we…