CEP Senior Advisor Sir Ivor Roberts writes: "On February 22, 1972, a month on from Bloody Sunday, the first Provisional IRA attack in Britain occurred. A car bomb detonated outside a Parachute Regiment barracks in Aldershot, killing seven civilians. An IRA statement the following day admitted the bombing as a revenge attack for Bloody Sunday, an event that still acts to tarnish the name of the Parachute Regiment. The parallels with recent events are striking, with the news cycling at one point between Bloody Sunday and a new republican bombing campaign in Britain. If we hope to keep a lid on violence in Northern Ireland - violence that is already spilling over to Britain - real political engagement between Sinn Fein and other parties in a restored Stormont is needed now more than ever."