An improvised explosive device exploded on a London Underground train on Friday morning, the latest terrorist attack to hit the British capital.

But experts, who have analysed footage of the device and assessed witness accounts, say the destruction would have been far worse if the bomb – which appears to have malfunctioned – had detonated as planned.

The bomb appears to be ISIS-favoured TATP – it just didn’t go off properly

The IED, which went off on a train at the Parsons Green Tube station, appeared to contain elements present in triacetone triperoxide, or TATP, a chemical explosive popular among Islamic State perpetrators, experts said.

“It’s very easy to dismiss this as a rather amateurish attempt, but I think looking at the evidence on the photos, it looks like a homemade explosive such as TATP, which is a very dangerous, volatile explosive substance that can be set off with very little agitation,” Richard Walton, the London Metropolitan Police’s former head of counterterrorism, told BBC Radio 4’s “Today” programme on Saturday.

When made properly, TATP – also known as “mother of Satan” – can inflict extraordinary damage. It was used in major attacks in Paris, Brussels, and Manchester.

Some experts speaking immediately after the attack said the bomb didn’t appear to contain elements of TATP. Ben Wallace, the UK’s security minister, confirmed on Saturday, however, that the Parsons Green bomb “used the type of explosive similar to that used in Manchester.”

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Foto: Forensic officers examining the site of the attack on Friday. source AP

Frank Gardner, the BBC’s security correspondent, said the Parsons Green bomber failed to make the bomb properly.

“They [bomb makers] have got to get the compound and mixture right, and in this particular case, the mixture was wrong, and the bulk of that explosive didn’t go off,” Gardner told the “Today” programme on Saturday. “It could have been far, far worse.”

Preliminary evidence “does suggest, or at least certainly lean toward, a lone individual and not an orchestrating cell sent over from Raqqa” had created the IED, Walton added.

Two anonymous US law enforcement and intelligence officials also told Reuters on Friday that the device “doesn’t look very professionally built,” and that the design suggested the attack was perpetrated inspired by Islamic State propaganda rather than a groomed member of a terrorist cell.

“We’re very fortunate because the bomb maker was incompetent,” Stephen Roberts, a former deputy assistant commissioner at the Met told Sky News on Friday.

The residue of Friday’s bomb is currently undergoing forensics at Fort Halstead, the Ministry of Defence’s research site in Kent, Gardner said.

‘Premature detonation’

Will Geddes, the CEO of security advisory group International Corporate Protection, suggested that the bomb might have gone off earlier than planned, given that Parsons Green is one of the smaller Underground stations on the line.

I know PG and District Line very well. If was #terrorism related, it could have been a premature detonation as #ParsonGreen not obv target https://t.co/QUWWtg7lOL — will geddes (@willgeddes) September 15, 2017

Parsons Green “doesn’t sit in the type of profile that terrorists wants for a detonation,” Geddes told The Sun on Friday.

If the explosion took place in larger stations, like “Notting Hill or Paddington Station, then you’ve got a much more identifiable location for the world to pick up on,” he said. Those stations, which are major interchange points, would also have had far more people inside.

Foto: A bomb-disposal squad near the Parsons Green Tube station. source Hannah McKay/Reuters

‘Looks like a fairly rudimentary device’

Geddes added that the lack of damage around the IED indicated that it was quite crude.

“I don’t see a considerable amount of scorched surfaces around the device itself,” he told The Sun. “It looks like a firework bucket – [the explosion] actually went up and not outwards.”

“I would say it’s an ill-conceived device,” he added.

Raffaello Pantucci, the director of international security studies at the Royal United Services Institute, also weighed in, telling The Sun: “It looks like a fairly rudimentary device.”

“It looks like someone has tried to build something out of explosive materials in a plastic container and shrouded it in a plastic bag on the outside.”

‘A low thud, rather than a loud crack’

Eyewitness statements of the detonation also indicated that the bomb was not as powerful as the attacker might have hoped.

“They [eyewitnesses] said they heard a low thud, rather than a loud crack. They described a sheet of flame, a fireball, rather than a blast,” BBC correspondent Tom Symonds told the network’s lunchtime news programme on Friday.

“That suggests that this was a device perhaps very poorly constructed, which went off before expected.”

As of Monday morning, British police had arrested two suspects linked to the attack. British media identified one of the suspects as 21-year-old Syrian refugee Yahyah Farroukh.