The suspect called 999 almost an hour before a farmer driving home called the police after seeing three vans surrounded by men in balaclavas, according to the report.
The motives of the caller are still under investigation, as the authorities are unsure if the suspect was attempting to sincerely stop the operation or if it was part of the larger plan.
Police are investigating the motives behind the operation itself after no explosive devices were found as part of their investigation, and are considering if the suspects were conducting surveillance, testing security, or trying to send a message to the British government, The Times wrote.
Police said that searches of London properties had been carried out as well as the vehicles at the scene, but while a significant quantity of fuel was found, no explosive devices were present.
“I understand why this development will have come as a surprise to many, but I’d like to reiterate that it was an investigative decision, and one which is grounded in experience and careful consideration of policing powers,” Taylor said.