THOUSANDS of bombs dropped on British cities more than 70 years ago by the Nazis never actually exploded and remain hidden "ticking time bombs" under our streets and roads.
From time to time they are uncovered and often lead to temporary evacuations. But how dangerous are they and what have been some of the most recent finds?
Are unexploded WW2 bombs still dangerous?
Experts say many of the bombs are unlikely to explode but are still a major hazard if mishandled.
Matt Brosnan, a historian at the Imperial War Museum, told the BBC: "The risk is in their unpredictability, they are inherently unstable and still contain explosives, which is why they are treated so seriously and have to be disposed of properly and safely."
Many were simply "duds" because of poor wartime manufacturing, while others suffered damage to the clockwork time-delay that detonates the bombs.
Chemical degradation of the fuse could also make the discarded devices lethal.
Simon Cooke, a former British Army major and leading EOD specialist, told the BBC: "Just the scrape of a workman’s shovel hitting the bomb body or the fuse packet could cause a chain reaction.
"It would do it instantaneously.
"The whole thing would be gone in hundredths of a second and you would be dead.”
A worker was killed in 2014 when his digger accidentally struck a WW2 bomb on a construction site in Germany.
How many unexploded war bombs could be discovered?
The scale of potential devices in London alone is alarming.
Germans bombed the capital in 85 major raids during the nine-month Blitz - dropping 24,000 tonnes of high explosives.
But 10 per cent of these bombs didn't actually detonate, says Mr Brosnan.
Some 15,000 devices, including grenades, were removed from construction sites between 2006 and 2009, according to the Construction Industry Research and Information Association.
And five per cent were live, which is equivalent to roughly 250 devices a year.
Birmingham, Liverpool and Plymouth were hit eight times and Bristol on six occasions during the Blitz as Hitler tried to destroy Britain's industry.
The Luftwaffe also targeted Glasgow, Southampton, Portsmouth, Hull, Sheffield, Coventry and Manchester.
It is estimated that there's also around 150,000 unexploded bombs under German towns and cities, steadily growing more and more unstable.
German cops evacuated some 50,000 people in May from Hanover to defuse five World War II era bombs.
The city was hit 125 times by Allied air forces during the war.
What have been the recent findings?
- February 2018: Another unexploded bomb was found in the Thames near the Dartford Crossing, closing the tunnel and bridge crossings
- February 2018: An unexploded bomb in the Thames near London City Airport saw flights cancelled as the airport closed
- September 2017: Tottenham Hotspur's training ground in North London and a few residential homes were evacuated after the discovery of a suspected WW2 device
- July 2017: Southend seafront was closed after an unexploded WW2 bomb was unearthed
- June 2017: The London Eye was evacuated after a tourist spotted a "World War 2 bomb" in the River Thames
- June 2017: Pensioner found an unexploded World War Two bomb in a cupboard under the stairs in Coventry
- May 2017: WWII bomb which brought Spaghetti Junction in Aston, Birmingham, to a standstill was detonated in a huge explosion (see video below)
- April 2017: Discovery of device in Putney, south west London, put this year's Oxford vs Cambridge Boat Race in jeopardy
- March 2017: Army scrambled to north London after a device was discovered
- February 2017: Bomb containing 290lb of 'high explosives' was found in Portsmouth harbour halting ferry and train travel.
- February 2017: Shoreditch High Street in London was evacuated amid fears of a 'possible WW2 bomb'
- January 2017: London was put on lockdown sparking chaos after an undetonated bomb was found in the River Thames - just yards from the Houses of Parliament
- January 2017: Streets were evacuated after a punter took unexploded World War One explosive into a pub in Swansea – after buying it at a car boot sale
- May 2018: A live German sea mine washed up on the Sussex coast on Elmer Beach near Bognor Regis.