The owner of a restaurant destroyed in an arson attack was "staggered" to learn a passing police officer failed to confront a man lighting a fire in her doorway shortly before.

GB Pizza Co in Margate was engulfed by a devastating blaze started by Andrew Miller, who would later sing “I’m a firestarter - a twisted firestarter” when taken into custody.

His actions in the early hours of October 9 last year wrecked the award-winning eatery days after a £20,000 refurbishment and risked the lives of nearby residents.

And now it has emerged the disaster could have potentially been prevented by a police officer who saw Miller feeding cardboard into a 1ft-high fire in the restaurant's doorway shortly before the flames spread.

The officer would later report why they had not intervened, saying they believed the man “appeared to be warming himself by a small fire” they deemed not to be a risk.

Details of the missed opportunity emerged as Miller, 48, was jailed for four years after admitting arson with recklessness as to whether life was endangered.

Sentencing him at Canterbury Crown Court, Judge Douglas Marks Moore said: “It is rather bizarre that the police had seen him on an earlier occasion, a man burning up cardboard, and did not stop to check.

“There were buildings nearby where people had to be evacuated; that in itself is the great danger of arson, that there could be significant loss of life or significant injury.”

Restaurant owner Lisa Richards, who is still uncertain when she will be able to reopen the business, described the police officer's actions as "utterly staggering".

"The last six months has been absolutely bloody awful, and this piece of information has completely floored me," she said.

"I’m struggling to find words as to how I’m feeling right now; kicked whilst down.

"At present, we don’t know when we’ll have the keys back to our restaurant, and now this has completely winded us."

After the officer failed to intervene, another eyewitness, David Lewis, saw Miller feeding cardboard into the fire outside GB Pizza Co and challenged him shortly before 4am.

Prosecutor Peter Walsh told the court: “Mr Lewis said ‘you need to put that fire out’; the defendant said something but he couldn’t understand.

“Mr Lewis then proceeded and walked back towards GB Pizza and then saw that a big fire was now coming from the doorway.”

Miller could be seen standing about 300 metres away “wrapping something around his head”, and then ran off, the court heard.

Mr Lewis alerted the emergency services and fire crews managed to fight back the flames.

Investigators later said the blaze would have spread to adjoining terraces in Marine Drive, with “devastating consequences” for sleeping residents.

Police arrested Miller after finding him nearby at about 4.20am, smelling of smoke and coughing continuously.

In custody, officers heard him singing the lyrics of The Prodigy’s 1990s dance classic Firestarter.

In a confusing police interview, Miller, of Eaton Road, Margate, said he set the fire because he was freezing cold, with the blaze soon becoming out of control.

But he then denied any part in igniting the cardboard before admitting his actions in court at the first opportunity.

A victim impact statement from Mrs Richards was read out in court.

“My biggest reaction is what impact this will have on the livelihood and mental wellbeing of the people who work for me," she said.

“This has totally destroyed months of work; I’m terrified about what will happen to my staff and myself.

“This is detrimental to my mental health, and even now I can feel I’m in shock and unable to process what happened.

“The premises is a community hub; we have various events and charity events based here.

“This act of senseless action has now removed a community staple - this will dramatically impact our personal and home lives.”

The award-winning pizza restaurant, which had just been refurbished to mark 10 years in business, has been operating since 2012.

The devastation attracted a swell of support from the Margate community, with people pulling together to help with the clean up.

Miller’s lawyer Max Reeves said he suffered addiction issues and a psychiatric condition, while the fire was “reckless behaviour rather than anything intentional”.

Kent Police said the officer who passed by Miller had been on their way to collect a missing child who had since been found when they “spotted a man who appeared to be warming himself by a small fire”.

A spokesperson added: “As the fire appeared to be under control and not posing a risk to the man or any other member of the public, the officer continued with their duties and later reported what they had seen.”

Police say they do not have a custody image of Miller to release.