A 500kg bomb discovered in the back garden of a house in Plymouth has been removed safely – but not without one of the largest evacuation operations since the end of the Second World War, involving more than 10,000 residents.

Around 30 of the Armed Forces’ most experienced bomb disposal experts from the British Army and Royal Navy worked around the clock since Tuesday to assess the condition of the bomb.

However, on Friday it was successfully removed from a densely populated residential area, and towed out to sea, where it is scheduled to be detonated in the next 24 hours.

It was discovered in the Keyham area of Plymouth, Devon, with a 300-metre cordon initially forcing an estimated 3,250 people out of 1,219 properties.

A further 300-metre cordon was then established along the route the bomb took as part of a military convoy on Friday afternoon, forcing thousands more out of their homes.

Trains, ferries and buses were cancelled as part of the operation.

West Cornwall Search and Rescue Team were among the hundreds of volunteers and emergency services drafted in to offer support.

The operation prompted the first ever use of the Government’s Emergency Alert system in a non-test context. Residents in Plymouth received an update to their phones warning them of the transportation of the bomb to the Torpoint Ferry slipway, along with an estimated timeframe for the movement.

Falmouth Packet: Police at the cordonPolice at the cordon (Image: Matt Keeble/PA)

The munition, identified as an air-dropped German bomb from World War Two – designated SC-500 – was assessed as posing a significant risk to public safety.

Plymouth City Council, with support from Devon and Somerset Fire and Rescue Service, Devon and Cornwall Police, and members of the Armed Forces, led a major operation to safely evacuate more than 10,000 residents from the vicinity of where the bomb was found, then from the surrounding area of the route it was transported along today before it was taken to sea.

Defence Secretary Grant Shapps said: “I would like to express my thanks to all our personnel involved in this highly complex operation, who worked both night and day this week to keep the public safe and minimise the risk of damage, as well as the public for their patience and cooperation.

“The success of this operation is testament to the level of skill and expertise across our Armed Forces, as well as the bravery and fortitude of our personnel when faced with high-risk situations and working under extreme pressure.”

Falmouth Packet: West Cornwall Search and Rescue volunteers were among the emergency servicesWest Cornwall Search and Rescue volunteers were among the emergency services (Image: West Cornwall Search and Rescue)

The complex disposal operation required hours of careful analysis by Explosive Ordnance Disposal (EOD) experts from both the Army and Navy, supported by specialist scientific advice from the Defence Science and Technology Laboratory, to establish the condition of both the explosive payload contained within the bomb – and the status of its fuse – before further action could be taken.

If the fuse or the explosive payload had significantly degraded, it may not have been possible to move the bomb and there would have been a significant risk of an uncontrolled explosion – with several residential houses within the projected blast radius.

After careful assessment, it was decided that moving the bomb would present a lower risk to the residential area – and it was transported in a convoy to a slipway near the HMNB Devonport base, before being towed behind a Navy vessel and submerged to a safe depth at sea.

Royal Navy divers are scheduled to plant an explosive charge on the bomb in the next 24 hours, to complete the disposal operation.