Tucked discreetly beneath the polished glamour of Burlington Arcade, London’s most historic luxury shopping strip, lies a speakeasy so seductive it feels almost imagined. No Regrets, the newest and arguably most intriguing addition to Mayfair’s drinks scene, is a blood-red hideaway concealed beneath British rock ’n’ roll jeweller Stephen Webster’s boutique, a bar that demands you seek it out, not stumble upon it.