A serving London police officer has been arrested in connection with the disappearance of Sarah Everard, in a development described by senior officers as shocking and deeply disturbing. Everard, 33, was last seen a week ago, as she walked from a friend’s house in South London to her home near Clapham Common. On Tuesday night, the Met police announced that they had arrested one of their own in relation to her disappearance, along with a woman who is suspected of assisting an offender. The officer was not on duty at the time Everard went missing, police said. “The arrest this evening is a serious and significant development,” Assistant Commissioner Nick Ephgrave said in a statement. “We will continue to work with all speed on this investigation but the fact that the arrested man is a serving Metropolitan Police officer is both shocking and deeply disturbing. “I understand there will be significant …