A SERVING prisoner who climbed to the top of HMP Guys Marsh before stripping off and setting fire to the building – causing millions of pounds worth of damage - chanted: “The roof, the roof, the roof is on fire.”

Nigel Saunders was seen on CCTV swigging from a five-litre bottle of homemade hooch before taking his prison-issue sweatshirt and jogging bottoms off, turning them inside out and setting them ablaze on March 10 this year.

The resulting fire caused extensive damage to a wing of the prison. Demolishing and rebuilding the wing will cost the taxpayer an estimated £20m. A total rebuild without demolishing the wing will cost £6m.

Prison officers were forced to evacuate 64 men from their cells after the fire took hold in just minutes.

Saunders appeared at Bournemouth Crown Court for sentence yesterday afternoon after admitting a single count of arson reckless as to whether life was endangered.

Simon Jones, prosecuting, said the defendant, 29, was serving a two-year sentence for burglary and theft offences at the time of the blaze.

He climbed to a flat roof before setting the fire in a sheltered area shortly before 7.15pm as other inmates egged him on.

“[He said] ‘I’m going to cause these ***** some mayhem’,” the barrister told the court.

Body-worn video recorded by prison officers was shown to the court.

In the footage, one officer can be heard shouting at Saunders to extinguish the fire, adding: “That’s arson to endanger life – put it out.”

However, the defendant can instead be heard singing: “The roof is on fire – we don’t need no water, let the ************ burn.”

Officers directed a hose at the roof to try and extinguish the fire before the emergency services arrived at the prison.

But Saunders stood in front of the jet to protect the blaze. Within minutes, the flames had reached the roof cavity.

The defendant was heard shouting: "I put Bridgwater on the map now.

"I don't give a ****. I'm in it for the long run.

"I'm at the point of no return."

He later said: "At least it'll make the papers.

"Burn, ************, burn. Black smoke, black smoke. Boom."

More than 100 firefighters from three counties were called to the scene at the height of the fire.

Saunders, who is currently incarcerated at Winchester prison, eventually surrendered shortly after midnight. In an interview with police, he said he owed a debt for synthetic cannabis Spice and had requested a prison transfer.

“I feel guilty as ****,” he told officers, adding: “I feel sorry for my actions but that won’t make it any better.”

Fire investigators later concluded the roof was “extremely combustible”.

Saunders has 30 convictions for some 73 offences. While serving a previous sentence at HMP Guys Marsh four years before the fire, he climbed onto the roof with two of his fellow prisoners and threw missiles and debris at guards.

Patrick Mason, mitigating, said the defendant first began offending at the age of just 11, and started drinking and smoking cannabis at 12. Saunders’ father was in and out of prison during his childhood, the barrister said.

“By the time he was an adult, he was absolutely entrenched in criminal conduct,” Mr Mason said.

“When he is intoxicated to the extent he has been, then things can go badly wrong.”

Sentencing Saunders to seven years in prison, Judge Jonathan Fuller QC said the defendant had shown "utter disregard" for the lives of inmates.

"It was planned, it was deliberate," he said.

"You were boasting and bragging and threatening in your manner.

"You were malign in your intent. You steadfastly refused to be reasonable."