Police have been banned from arresting foul-mouthed yobs who abuse them with the most offensive swear words in the language. The rule change, which has sparked a revolt in the force and anger among MPs, is revealed in secret advice issued to officers and leaked to The Mail on Sunday. Scotland Yard has issued a card to its officers, telling them to do nothing if they are subjected to a torrent of obscene abuse. The card, which the police are told to keep on them, secreted behind their warrant...