PORTSMOUTH HARBOUR BOMB ALERT: The story so far

Dredging works are being carried out ahead of HMS Queen Elizabeth

On September 10, police sealed off up to 500 metres of the area after a rare British torpedo, dating from the Second World War, was found at around 5am.

Then on September 30, bomb experts carried out a controlled explosion of a 500kg German bomb, similar to that of the one discovered this morning in the harbour.

The discovery, the day before the detonation, prompted an evacuation of punters and businesses in Gunwharf Quays, while bomb disposal experts removed the German device.

The devices each time have been found on the seabed whilst contractors carry out dredging works in the harbour ahead of the arrival of the navy’s new 65,000 tonne state-of-the-art HMS Queen Elizabeth next spring.

In June 2015, a lucrative contract worth £31m was awarded to Fareham-based Boskalis Westminster Ltd to ready the harbour for HMS Queen Elizabeth as well as HMS Prince of Wales, due to arrive in the city by the end of the decade.

The carriers will be far larger than any ships currently using Portsmouth Harbour, so Boskalis has been dredging the approach channel, inner harbour area and berth pocket, making them deep and wide enough to accommodate them.

Around three million cubic metres of clay, sand and gravel are being removed from the harbour by the trailing suction hopper and backhoe dredgers.

The dredge is part of a programme of work by DIO to prepare for the arrival of the carriers, which includes rebuilding an ageing jetty dating from the 1920s.