Counter-terrorism detectives arrested a second man over the bombing of a London Underground train on Friday (15 September) that injured 30 people and the security services lowered the threat level for an attack from its highest setting. The 21-year-old man was detained under Britain’s terrorism laws in the west London suburb of Hounslow just before midnight on Saturday, Scotland Yard said in a statement. Police had earlier arrested an 18-year-old male in the departure lounge of Dover port in what they called a “significant” step and raided a property in Sunbury-on-Thames, a town near London and about four miles (six km) from Hounslow. The home-made bomb shot flames through a packed carriage at Parsons Green Tube station in southwest London during the Friday morning rush hour but apparently failed to detonate fully. Islamic State claimed responsibility, as it has for other attacks in Britain this year, including two in London and one at a concert by American singer Ariana Grande in Manchester in May. Home Secretary Amber Rudd said on Sunday the second arrest showed …