The Royal Navy carried out a controlled detonation of a 1000 Lb WW II bomb penetration bomb that they had discovered during a survey of the River Mersey around midnight on the 15th May. The bomb was picked up on sonar off the Twelve Quays ferry terminal at Birkenhead, by the Mine hunters HMS Walney and Atherstone, who where conducting a survey of the River Mersey.
Lieutenant Commander Richard Pethybridge, captain of HMS Atherstone, said, "Of all the mines planted on the seabed during World War Two, only 25% have ever been discovered. While the detonators may no longer work, the explosive charge is often still working."
As a result, Merseyside Police and the Marine and Coastguard Agency established a 200-metre exclusion area around the scene and shipping was held at the Mersey Bar. Navy divers had to wait until the strength of the current in the Mersey subsided sufficiently to allow a buoyancy aid to be attached to the bomb. This then enabled the divers to lift it to a depth of three meters and attached a line to the bomb and tow out by rib to the North Bar Light, where it was lowered on to the Sea Bed before being destroyed by a controlled detonation about 21:00 on the 16th May.
Both of the Vessels had been open to the public on Saturday whilst they where berthed in Canning Dock part of the Albert Dock Complex in Liverpool.
HMS Walney and HMS Atherstone berthed in Canning Dock