© Licensed to London News Pictures. 23/03/2017. London, UK. A vigil is held in Trafalgar Square, London, to remember those killed in the Westminster terror attack, the day after a lone terrorist killed 4 people and injured several more, in an attack using a car and a knife. The attacker managed to gain entry to the grounds of the Houses of Parliament, killing one police officer. Photo credit: Ben Cawthra/LNP