In the row behind me as I wait for Michael Portillo to arrive on stage, two young men are talking in clipped, plummy accents – so posh they seem almost to be speaking a different dialect – about shooting. “She’s gottuh gun,” says one. “She’s not shot for about five years. But she’s gottuh gun.” I frown. We are in Cadogan Hall, just north of Sloane Square; surely the lady in question should own a pair of shotguns? Are the residents of Chelsea suffering an unreported cost-of-shooting crisis?