A Muslim English teacher yesterday today pleaded guilty to threatening to blow up the giant Bluewater shopping centre.
Saeed Ghafoor said he was going to bomb Europe's largest shopping complex using three limousines with gas canister explosives.
But when questioned further, the former English teacher said Bluewater was in Exeter, the Old Bailey heard.
When told it was near the Dartford tunnel in Kent, Ghafoor said he had not 'finalised' his plans, the Old Bailey was told.
Ghafoor, 33, of Southampton, pleaded guilty to threatening to cause criminal damage.
He was remanded in custody for reports before sentencing next month.
The Bluewater centre was the target for a gang of terrorists led by Omar Khyam who were jailed for a fertiliser bomb plot last year.
Ghafoor made his threat to prison officers at Haverigg jail in Cumbria in February this year.
He was serving a 12-month sentence imposed by Southampton Crown Court in January for threats to kill his sister and assault.
The court was told he had grabbed her round the throat and also threatened her with a knife.
After being released on licence on March 7, Ghafoor was arrested and taken to Carlisle police station, where he was questioned and charged.
Prosecutor Pierce Arnold said he was now in Wandsworth prison as his licence had been revoked.
He said: "This matter is not a bomb hoax. Mr Ghafoor made the threat and it was treated seriously.
"We do not know if he could have carried it out. It was not a bomb hoax. It appeared on the face of it to be a serious threat by someone who was not happy."
Mr Arnold said the first prison officer he spoke to formed the impression that Ghafoor was a "fantasist" but took the threat seriously.
Senior prison officer Dawn Pugh then went to see him and he told her: "I am planning to bomb Bluewater shopping centre in Exeter."
Mr Arnold said: "He was going to blow up Bluewater shopping centre with three limousines packed with explosives."
Another prison officer had pointed out that Bluewater was in Kent. Ghafoor told him: "The plan is not finalised yet."
He said he was protesting at the involvement of British and American troops in Afghanistan.
He was seen by the prison imam, who formed the impression that Ghafoor was susceptible to brainwashing.
After his arrest, a psychiatrist told police he had no mental disorder, said Mr Arnold.
Bearded and balding Ghafoor, who appeared in court by video-link, was said to have a history of domestic trouble which resulted in him threatening to destroy property..