Britains top counter-terrorism officer Assistant Commissioner Bob Quick has resigned after his security blunder threatened a major anti-terror operation. London Mayor Boris Johnson said he had accepted the resignation with "great reluctance and sadness". Asst Comm Quick said he deeply regretted the disruption caused to colleagues when he inadvertently revealed details of the counter-terrorism operation. Asst Comm Quick faced little option but to step down after he was pictured clutching sensitive documents as he arrived in Downing Street for a meeting with the Prime Minister and Home Secretary. The top sheet of the file, which included names of terror suspects, locations and officers involved in the operation, was clearly visible to photographers and cameramen.