The explosion in a taxi outside Liverpool Women's Hospital on Sunday has been confirmed as a terrorist incident by police and is currently under investigation. Defence and security experts at Cranfield University give their initial views on the explosion as seen on the CCTV video released of the incident:

Jacqueline Akhavan, Professor of Explosive Chemistry and Director of Education for Cranfield Defence and Security, said: “I could not see a blast wave, therefore this was not a detonation. This was probably due to a malfunction of the device. This is why the driver survived. The white cloud is most likely due to unexploded ammonium nitrate. The only fragmentation I could see was parts of the car, so I am assuming that it was not a pipe bomb.”

Trevor Lawrence, Director and Senior Lecturer in explosives and munitions at Cranfield Ordnance Test and Evaluation Centre (COTEC), said: “There is no obvious blast wave and very little damage to the body of the car, indicating that there was no detonation. The windows were blown out and a large cloud of white smoke was seen. This could mean that either the device contained a low explosive or did not detonate as designed, which is common in home-made explosives.

“The fact that the driver survived and the passenger was killed makes it likely that the passenger was in close contact with the device, either in the form of a rucksack or suicide belt.  The source of the explosion appears a relatively small charge positioned on or near the rear seat.

“The large cloud of white smoke, subsequent fire and lack of structural damage strongly indicates a low explosive charge, possibly gunpowder and most likely extracted from fireworks.  There remains the possibility that a larger high explosive charge failed to function correctly.”

Pete Norton, Researcher at Cranfield Defence and Security and former British Army Ammunition Technical Officer, said: “There are numerous possible factors why the event unfolded as seen but, based on initial open-source reporting, and the video footage, it is most likely that any explosive device that the back-seat passenger was (reportedly) carrying/wearing only partially functioned. In my extensive experience of scene-of-explosion investigations, the damage to the car (visible in the CCTV) and survival (with injuries) of the driver, would be commensurate with such a scenario.”