The ambulance service were put ‘on standby’ the day before the suspected terrorist incident at RAF Fairford, Wiltshire 999s understands.
A source has confirmed that the Hazardous Area Response Team (HART) were warned of a potential attack and had prepared on Saturday (26 September).
It came as the security threat level at the US airbase was raised to FPCON Delta, the highest US military force protection condition and is used when a terrorist attack has occurred or intelligence indicates terrorist action is likely.
Information suggests emergency services were already preparing for a heightened security threat at RAF Fairford some hours, if not days, before five men were arrested near the base in the early hours of Sunday (27 September).
Locals claimed that only recent had physical security at the airbase been increased, with large military vehicles and machinery positioned across unmanned entrances to RAF Fairford.
It is not known what intelligence prompted those measures, or whether the heightened security was directly connected to the five men subsequently arrested.
But the revelations take on new significance after Prime Minister Andy Burnham said there are “strong indications” that Iran played a part in the incident.
The Prime Minister said the incident remains an ongoing, complex and serious police investigation, with British authorities working closely with the United States.
Iran has denied involvement.
The incident began at around 12.45am on Sunday when police received a report concerning three suspicious vehicles which appeared to be travelling towards RAF Fairford.
Armed officers responded and five British men, aged between 23 and 25, were arrested in the Whelford area.
They were initially arrested on suspicion of offences under the Explosives Act and were later further arrested on suspicion of preparation of a terrorist act.
The arrests triggered a huge emergency response involving Counter Terrorism Policing, armed officers, army bomb disposal specialists, fire crews and specialist ambulance teams.
Approximately ten HART ambulances were deployed, while Wiltshire 999s estimated around 100 police vehicles were in the area at the height of the operation.
A 400-metre cordon was established around the three vans and around 85 households were evacuated.
Bomb disposal specialists spent hours examining the vehicles, including with the use of a specialist robot.
Police subsequently confirmed that petrol was discovered during searches of the vans but no explosive devices were found.
The five men were released on police bail following “extensive interviews”, with police stressing that the decision did not mean the investigation had ended.
Mr Burnham has defended their release, saying they are subject to strict bail conditions and that authorities have the situation under close control.
RAF Fairford is operated by the US Air Force and has been used by American bombers involved in operations against Iran.
Iran previously warned that bases used for attacks against its territory could be considered legitimate targets.
Exactly why FPCON Delta was activated before Sunday’s incident, and what prompted emergency services to be placed on standby, has not been publicly disclosed.
