PEOPLE are being warned to watch where they dig because a new map shows you are more likely to find an unexploded Second World War bomb in south Essex than in other parts of the country.

The area from Thurrock to Southend is considered a high risk zone for bombs by a risk mapping company.

Zetica uses geophysics to provide risk assessment maps to building developers, but now the public can also check if they live in a hotspot area using an online map.

Zones are assessed by the density of bombing hits. In a high risk area, this means 50 plus bombs per 1,000 acres.

There is no doubt south east Essex, bordering the River Thames, was seen by the German Luftwaffe pilots as a strategic trade target.

On the other hand, it is also true Essex just had the misfortune of being the county on route to London.

Mike Sainsbury, managing director of Zetica, who took two years to produce maps for every UK county, said: “From Southend through to Thurrock you have a zone where German pilots would tip and run.

“They didn’t want to encounter the flak from the anti-aircraft batteries in London, so would drop their bombs earlier.

“There were the strategic sites too, from Shoeburyness through to the oil refineries in Thurrock.

“It is to be expected a number of bombs were dropped in that area.”

Historian Richard Smith, vice- chairman of Purfleet Heritage Centre, recalls the Purfleet refinery being bombed on September 7, 1940. He said: “They hit two of the tanks and there is a picture from the time which shows the smoke coming up from them.

“Ford factories would have also been targets, as were the anti-aircraft guns at Coalhouse Fort, in Tilbury, and at Horndon on the Hill.”

But for the ones that didn’t explode, he added: “There must still be lots of them lying around.

“A couple of years ago someone came into the heritage centre with a combustion engine from a V2 rocket, so they are still out there.”

Richard believes there could be another important reason why unexploded bombs landed here.

He explained: “There were a number of attacks using V2 and V1 doodlebug rockets.

“These landed on Essex as the Germans used to make them using slave labour.

“Because of this, workers would tamper with the navigation systems, or ensure the bombs didn’t detonate so it would not complete its mission or hit its designated target.”

The Zetica map is based on local authority records and Ministry of Defence files and reports on the German Luftwaffe.

The map refers to the types of bombs which could still be hidden, categorising them as high explosive, anti-personnel or incendiary devices.

The latter are considered the least dangerous. Mr Sainsbury added: “A lot of them didn’t even penetrate the ground and it’s very unlikely they would operate today.”

High explosive bombs were dropped in high numbers and anti-personnel devices included mines. Mr Sainsbury warned: “For every ten bombs dropped, it’s estimated one didn’t explode.”

Two years ago, Southend councillor, Brian Kelly, urged the council to carry out an archaeological dig on the old college playing fields in Lifstan Way, Southend, before flats and houses were built.

“This was because a German Junker 88 aircraft had crash-landed there on August 30, 1940.

The homes are now built, though, and fortunately no unexploded bombs have been dug up.

Mr Kelly, who was a navigator in the RAF for two years in the 1950s, said: “I called for the dig because the plane that crashed still had part of its bomb load on it.

“A number of bombs were found in the wreckage, but I didn’t know if all of them had been found and destroyed.

“I would expect there to still be a number of unexploded bombs yet to be found.”

To request a copy of the online map visit