A police marksman who shot a drunken barrister who had been firing a shotgun from a window at his home has said what he did was "absolutely necessary".
Mark Saunders, 32, was shot dead by police surrounding his £2.2 million property in Markham Square, Chelsea, on May 6 2008, at the end of a five-hour siege.
The officer, known only as AZ 12, to preserve his anonymity, told Mr Saunders' inquest that he thought Mr Saunders was going to kill colleagues on a nearby roof.
Mr Saunders had opened his kitchen window after firing from it during the stand-off.
The officer told Westminster Coroner's Court how he had been stationed as "a show of force" in cover at garden level at a house in Bywater Street, near Mr Saunders' home.
"It's a physical thing, a show of force," he said. "The gentleman knows he's surrounded. He can see me, I can see him."
He added: "I'm trained to be there as a show of force, the barrier between the public and the bad man. That's what I do, and that's what I did."
He described how after Mr Saunders opened the window he was "lowering the weapon towards my colleagues" on the roof of a neighbouring house. Asked if he shot Mr Saunders in self-defence, he said: "No, in defence of others." Asked what he thought was going to happen, he said: "I thought he was going to kill them."
And asked if it was necessary to fire to defend them, or was there any other action that could have been taken, he said: "It was absolutely necessary. I can't rely on their threat assessment of what I see in my position."
The inquest, sitting in Marylebone, has heard how the legal high-flyer sparked the siege when he fired his legally held shotgun while on the phone to a friend at 4.40pm after a lonely afternoon drinking binge.