Tehran has been trying to step up attacks on targets in the west but its track record has been mixed

Investigators may be some way from determining exactly what led five men with three vans to a village just outside RAF Fairford in the small hours of Sunday – but the fact they have all been released on bail without immediate charge suggests they are not deemed to pose a serious and violent threat.

In a moment where wider geopolitical tensions mean external threats are perceived to be close, the question of whether Iran had a hand in the alleged plot remains open. Nonetheless, the bailing of the men is a mercifully lower-key development in an investigation that appeared of the utmost gravity.