It is hardly surprising that intelligence chiefs raised the terrorist threat to severe on Monday. The failed attack outside Liverpool Women’s hospital came within a month of the killing of Sir David Amess MP at his constituency surgery in Essex.
Yet it had been hoped, cautiously, that the climate was changing. Two years ago the terrorism threat was downgraded to substantial, for the first time in five years, a month after the Islamic State leader Abu Bakr al-Baghdadi had been killed.
It had been at that lower level for most of the last two years, aside from an isolated three months in the winter of 2020-21, when there were heightened security concerns following Islamist attacks in Austria and France.
Now, it is less certain what lies ahead. Although there is much that is not known about what happened in Liverpool on Sunday – and in particular the motivation of the deceased suspect – security agencies do know that one terrorist attack can often inspire another, as happened in the UK in 2017.
“Severe” is the second-highest of the five threat levels used by Britain’s security apparatus. It means an attack is considered “highly likely” as opposed to to “substantial” where the threat is deemed likely. (The highest level, “critical”, means an attack is feared imminently and it has only ever been used for a few days at a time.)
But what will trouble investigators further is that Sunday’s incident was the first explosive attack in Great Britain since 2017. The most recent of those, at Parsons Green tube station in west London, in September of that year, featured an explosive device left on a train carriage at rush hour.
Witnesses described seeing a “fireball” and fled the stationary train, although 400g of home made TATP explosives mercifully failed to detonate. Nevertheless, dozens of people were injured in the incident, including 22 who suffered burns, although it clearly could have been much worse.
It looks likely something similar could be said for the explosion outside the Liverpool hospital. Whether it was the intended target of the attacker is not certain – police have only said it was where the suspect asked to be driven to in a taxi picked up a few minutes’ drive away.
Military experts say, having looked at the video of the explosion recorded by CCTV facing the hospital entrance, that it appears the device did not go off as intended. An initial detonation is not followed by a greater explosion, and remarkably the taxi driver was able to escape from the car seconds after.
Philip Ingram, a former military intelligence officer who studied the film circulating believes that, if fully detonated, a bomb that close to the hospital “would have blown the windows out, bowed the roof [of the car] and the glass wave would likely have killed both and put hospital windows out”.
It was only a few months prior to Parsons Green that the worst terrorist attack of the last decade and a half took place: the Islamist suicide bombing of the Manchester Arena, minutes after an Ariana Grande concert had finished. That night 22 were killed and many more injured after a homemade bomb exploded, a stark reminder of how deadly terrorism can be.
