The ringleader of the London Bridge atrocity tried to hire a 7.5-ton lorry just hours before the deadly attack, it was revealed last night.
Investigators suspect Khuram Butt, 27, wanted to kill and maim as many people as possible. But the martial arts expert's bank card was declined, forcing him to use a smaller B&Q van at the last minute.
As counter-terrorist police warned Britain faces an "unprecedented" risk of further vehicle attacks, shocking new details of the plot emerged:
• All three attackers carried identical 12-inch razor-sharp pink ceramic knives with hand-made leather grips, bound to their wrists by shoelaces;
• Their Renault van was packed with sacks of gravel and chairs, possibly to increase its weight as a 'battering ram';
• Police also found 13 Lidl wine bottles filled with lighter fuel and topped with rags to use as Molotov cocktails, as well as two blow torches to ignite them;
• The trio used a flat above a bookmakers as a 'safe house', leaving behind a copy of the Koran open on a passage about martyrdom.
A week after eight people were killed and dozens injured in the attack on the capital, police believe the three terrorists acted alone. Butt and his fellow extremists Rachid Redouane, 30, and Youssef Zaghba, 22, killed three people as their van drove through crowds on London Bridge.
After crashing into barriers, the trio fled the vehicle in separate directions, murdering five more before regrouping in Borough Market.
It was here that the suspected suicide bombers died in a hail of 46 bullets in chaotic scenes as they were confronted by eight police marksmen.
Each man was wearing a home-made fake suicide vests, constructed from plastic water bottles, black and silver duct tape and belts. Police believe they were planning to return to the van and launch a second wave of attacks with the potentially deadly petrol bombs.
Investigators have now discovered that Butt, a member of hate preacher Anjem Choudary's inner circle, attempted to hire a 7.5-ton lorry earlier that day.
When his bank card was declined, he asked neighbours where he could hire a van at short notice.
Police said a white B&Q branded vehicle was loaned at 6.30pm from a location in Harold Hill, Romford, using a "recently activated" mobile phone. It was then driven to Zaghba's address in Barking, East London, and then toured London before the fatal attack was launched just before 10pm.
Incredibly, CCTV shows the trio drove up and down the bridge to "scope" targets before suddenly performing a U-turn and driving into innocent pedestrians.
Detectives are appealing for help to trace the distinctive "exceptionally sharp" ceramic kitchen knives used by the attackers, which would not trigger metal detectors.
It emerged last night the knives may have been bought for as little as £4.99 (NZ$8.80) each. There were on offer at Lidl between May 4 and 10.
Police also discovered that a bedsit above a branch of Paddy Power in Barking, East London, was used as a "safe house", after being rented by Redouane in April.
Officers found rags similar to those in stuff the Molotov cocktails as well as the same water bottles used in the "suicide vests". There were also craft knives, phone chargers, bottles of superglue, pieces of rubber and plastic and rolls of duct tape.
When the bedsit was raided by armed police earlier this week, a young woman wearing pink hot pants was arrested and another man tried to escape through a window.
Commander Dean Haydon, who is responsible for Scotland Yard's counter-terrorism command, said Britain faced an "unprecedented" terrorist threat.
He warned that although the three men are believed to have acted alone, further arrests will be made. He said some of the 18 people held over the London Bridge attack were suspected of having knowledge of their plans, giving them money or encouraging them.
"We are in unprecedented times," he said. "At the moment we are doing everything we can alongside the security services to stop would-be attackers and keep the public safe.
"We have foiled 13 plots since mid-2013 and since the Westminster attack alone we have prevented and disrupted five attacks, but three have got through.
"The tempo we are working to is extraordinary. We are running 500 investigations into 300 people at any one time."