By pure chance the Sutton emergency response exercise, which had been planned for several months, came just five days after the terrorist attacks in Paris.
The borough's response was co-ordinated and controlled by a number of representatives from different organisations including Met Police and Sutton Council from the Borough's Emergency Control Centre set up at Sutton Police Station.
As part of the exercise, a survivor reception centre was also set up at Sutton Life Centre in Alcorn Close, Sutton, to look after the 'uninjured survivors' - many of whom were suffering from shock and trauma and had been subject to a white dust residue which had contaminated the air following the explosion.
To assist, London Fire Brigade set up their decontamination tent in the car park at the rear of the Life Centre where survivors wearing white suits went through a decontamination process.
Other organisations taking part at the Life Centre included the British Red Cross - administering first aid, counselling and humanitarian assistance; Met Police - taking details of survivors, witnesses and potential suspects; and Sutton Council - looking after housing needs as well as providing food and drink.
The simulated disaster was designed to test the borough's emergency procedures, co-ordination and collaboration including those of participating agencies when responding to a major incident. Its purpose was to help ensure the best support possible can be provided to residents and communities during such emergencies.
Cllr Jill Whitehead, Chair of the Environment and Neighbourhoods Committee at Sutton Council, said:
"Coming so soon after the terrorist atrocities in Paris, the emergency exercise took on an added urgency as it centred on a terrorist attack on the borough and how our emergency services were prepared and responded to such a horrific scenario.
"The exercise brought all of our emergency services together to cope with the aftermath of the attack and review our policies and procedures. By thinking the unthinkable we can help protect residents and communities should such a situation ever happen for real."
Sgt Simon Alexander, of Sutton Police Station, who was co-ordinating activities at the Sutton Life Centre, said:
"This is all about partner agencies working and training together to keep people safe - that's why these exercises are so important."
Under the Civil Contingencies Act 2004 it is a requirement for local authorities and the emergency services to plan for emergencies. The Safer Sutton Partnership Service (SSPS), which manages the borough's community safety services, runs an exercise every year - and this year was the biggest one ever organised in the South West London area.
More than 75 members of the public had volunteered to be uninjured survivors.
The SSPS would like to thank all the volunteers who took part and the many others who volunteered but were unable to take part because all the places had already been allocated.