The Russian Orthodox Cathedral in Knightsbridge is nestled in a maze of mews streets and embassy rows somewhere between Harrods and Hyde Park. It’s as much an expat social club as it is a place of worship, and on Sunday mornings it’s packed to the rafters. In what can sometimes look like one big game of Grand-mother’s Footsteps, the congregation of headscarved women and men in leather jackets quietly make a dash to circulate every time the priests turn their back, while old women maunder about kissing icons and hushing grandchildren.