Smith was arrested by armed police last Friday on Holloway Road in North London.Last Saturday, another device was discovered at an address in Devon leading to evacuations, however it was found to be not viable.The Met police has said more officers, including armed police, would be seen around “transport hubs” to reassure those with safety concerns.In a statement, the Met said: “Officers continue to encourage the public to remain vigilant and alert at all times, and report anything suspicious to police.” He is alleged to have made or acquired the substance between October 18 and October 21 contrary to section 3(1)(b) Explosive Substances Act 1883.The station was evacuated after the item was discovered last week, and the Ministry of Defence subsequently warned military personnel of the danger of a ‘severe’ threat on the Tube.A controlled explosion was carried out on the device, which was reportedly handed to the Tube driver and possibly had wires and a clock. A 19-year-old man has been charged with making or possessing an explosive substance with the intent to danger life in relation to an incident on the London Underground last week. Damon Smith, of south-east London, will appear at Westminster Magistrates’ Court on Thursday morning, Scotland Yard said. A “suspicious item” was found on a tube carriage on the Jubilee Line at North Greenwich station, near the O2 arena last Thursday. The teenager is charged with unlawfully and maliciously making or possessing an explosive substance with an intent to endanger life or cause serious injury to property, the Metropolitan Police said. The device was found at North Greenwich stationCredit:Daniel Leal-Olivas/AFP / Getty Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.