Emergency services, police and intelligence agencies will carry out the largest-ever rehearsal of a response to a terror attack across the city today. Exercise Strong Tower will involve more than 1,000 officers.
Armed gunmen were seen stalking through the streets of central London today as part of the biggest ever police training exercise for a terrorist attack.
The masked men were seen firing guns in the air and throwing what appeared to be grenade-like devices inside the disused Aldwych station.
Preparations for the exercise began around six months ago and events such as the Charlie Hebdo attack in Paris and the hostage siege in Sydney influenced the test, police said, stressing it was not connected to the Tunisia attacks.
The two-day exercise will see a test of the emergency service response to an attack at the disused Tube station at Aldwych. The vast majority of police officers involved have no idea about the venues or what is planned.
Only around 12 people knew specific details of what was going to happen in advance.
Among those taking part are all of London's emergency services, Greater London Authority, Transport for London, Home Office, Cabinet Office, Ministry of Defence, the Department of Health and NHS England.
The unlicensed events unfolded on Saturday night at Clapham Common and Tooting Bec Common.
A 37 year old man who was taken to hospital after getting into difficulty in a stretch of water near Maidenhead has died.
Jonty Bravery, who is mentally ill, has been jailed for 15 years after throwing a six year old boy from the Tate modern balcony.