The CPS says Dylan Earl’s been charged with involvement in the planning of an attack on a Ukrainian business in London in March.
Four other men, including one from Roehampton and two from Croydon, are also being questioned over their links to the case.
They’ll appear in court next month.
Commander Dominic Murphy, Head of the Met’s Counter Terrorism Command, which is leading the investigation, said: “This is a highly significant moment and investigation for us. Not only are the charges that have been authorised by the CPS extremely serious, but it is also the first time that we have arrested, and now charged anyone using the powers and legislation brought in under the National Security Act.
“We have spoken publicly in recent times about various threats linked to national security that we have been facing, and the increase in operational activity required across Counter Terrorism Policing to meet these.
“While these are very serious allegations, I want to reassure the public that we do not believe there to be any wider threat to them in connection with this matter. This investigation remains ongoing, but now that charges have been brought about I would urge everyone to respect the criminal justice process and not to speculate or comment further in relation to this case.”
