Trident nuclear programme. In February 2008, five campaigners from the Plane Stupid group gained admittance to the building as visitors and then moved up to the roof to demonstrate against the proposed expansion of Heathrow Airport; from there they hung two banners they had smuggled past security. MPs and security experts found it worrying that the protesters made it to the roof in spite of the heightened security measures, and the prosecution at the activists' trial argued that they may have received help from a House of Lords employee. In October 2009, at least forty Greenpeace activists climbed to the roof of Westminster Hall to call for the adoption of policies combating climate change. Some of them climbed down after nearly five hours, while the rest spent the night on the roof. On 22 March 2017 an Islamist-related terror attack happened in which a man stabbed a police officer after ploughing into pedestrians on Westminster Bridge. Five people were killed, including the attacker and the police officer. In August 2018 there was another attack, treated by prosecutors as terrorism. On 1 April 2019, a group of environmental protestors from the group Extinction Rebellion stripped semi-naked in the public gallery during a Brexit debate and glued themselves to the handrail and glass screen with their buttocks facing the Commons Chamber. MPs attempted to continue the debate, some of them incorporating puns and references to nakedness into their speeches, to much hilarity. There have been four fires on the Palace of Westminster site during 2019, and eight in 2018. In 2022, the body of the late Queen Elizabeth was left inside the hall for people to pay their respects. A man decided to jump the barriers and pull away the flag draped over the coffin. He was detained and taken away by police and officials. Rules and traditions The Palace has accumulated many rules and traditions over the centuries. Eating, drinking and smoking Smoking has not been allowed in the chamber of the House of Commons since the 17th century. As a result, Members may take snuff instead and the doorkeepers still keep a snuff-box for this purpose. Despite persistent media rumours, it has not been permitted to smoke anywhere inside the Palace since 2005. Members may not eat or drink in the chamber; the exception to this rule is the Chancellor of the Exchequer, who may have a beverage of the