sentences:  Mark continued to root out corruption, ably assisted by his Deputy Commissioner, Sir James Starritt.He also had to deal with the increase in IRA terrorism, including the Balcombe Street Siege, and also the Knightsbridge Spaghetti House Siege, taking personal command of both.Although popular with liberals for his stamping out of police corruption, Mark was himself far from a liberal, had no time for anti-establishment demonstrators and such groups as the National Council for Civil Liberties, and was responsible for the introduction of the Special Patrol Group, whose paramilitary methods provoked considerable criticism.