At age 69, Les Duncan remembers the sturdy boots he was wearing the day he walked inside Peterhead prison, the floors completely flooded.

"The first thing they do during a riot is burst all the pipes," he said.

The former Scottish Prison Service negotiator, based at HM Perth, was brought in on the fourth day of one of the worst jail sieges in Scotland.

In 1987 violence was spreading through the country's lock-ups like a raging virus. Peterhead inmates followed in the footsteps of those at Barlinnie, which claimed the country's longest riot that year. Perth would riot days after Peterhead.

On October 3, around 50 dangerous convicts including murderers and rapists seized control of D block in Peterhead jail, a notorious institution known as 'The Hate Factory'.

Prisoners unleashed their anger on the environment they despised. Ringleaders took two prison officers hostage, beat them and held them captive for five days.

One officer, Jackie Stuart, was chained, stripped and paraded on the roof 90ft above ground.

"Riots were quite a common occurrence and it was the same with suicides as well," said Les from his home in Falkirk.

"When one person committed suicide then somebody else committed suicide. If one jail had a riot then another jail had a riot.

"Some suggested it might have been planned, but I don't know.

"The atmosphere was very very tense. Once the prisoners had got back into their cells they made as much noise as they possibly can.

"It was just a ruckus of noise, rattling their bed frames and shouting at each other through their windows."

It was perhaps a stroke of fate that Les found himself involved with the men responsible for the hostage situation.

He arrived at the north east jail thinking he was assigned to riot control, never having set foot in the place before. "We were going in blind," he said.

But the team were short of men who could negotiate, and a psychologist who knew Les from HM Perth put him forward for the daunting job.

As second in command, Les was first confronted with Malcolm Leggat - a man jailed for life after he murdered a 23-year-old man in Glasgow.

Leggat not only started the riot, but stabbed an officer and threw hot fat at him. While he hurled debris from the roof at any officer who tried to get near, Les stood on the floor underneath him.

"That was the second time I had heard Malcolm Leggat's name," said Les. "The week before, I was standing up on the roof of Perth prison where Malcolm tried to kill me.

"He threw slates at me and he had been sent up to Peterhead because of his behaviour.

"I never negotiated with him again after that."

In the end Les didn't exchange words with Leggat - another member of the core group moved to another part of the rooftop and was calling to guards below.

He found himself vulnerable, looking skyward at Sammy 'The Bear' Ralston, serving six years on an armed robbery charge.

One of the banners hanging from the prison's roof during the riot read "Sammy Ralston was tortured." As he stood talking to Les through a skylight, he sprayed him with lighter fluid.

"I never thought I was in danger," said Les. "You have a team behind you when you're negotiating - in a second they would rush in and grab you and pull you out.

"I didn't know Sammy at all. I don't really know what he wanted. He was trying to tell me he had nothing to do with the riot.

"I'm not sure if I did calm him down. The negotiating co-ordinator was having a hairy fit because he didn't think I should have been there. But to be perfectly honest, had I been anywhere else I couldn't have talked to him, because I couldn't see him."

Les was unaware of his narrow escape with Ralston. After the tense encounter, he finished his shift, situation unchanged.

The seige concluded while Les was in bed in a nearby hotel - Prime Minister Margaret Thatcher made the controversial decision to send in the SAS to storm the building.

Ralston's group were about to set Jackie Stuart on fire when they arrived. SAS officers were armed with flash-bang grenades and gas grenades.

Les and his colleagues had nothing but fire-proof overalls and batons. A year later riot gear would become the standard clothing for Peterhead officers when Andrew Coyle was made governor.

Now, 29 years after the rampage, Les lives out his retirement with wife Lynda, having left the prison service in 2002.

The pragmatic Scot claims the job never truly affected him. His family on the other hand tell a different story.

Lynda said: "We'd had one seige after another, then came the Perth one and we'd just about had enough.

"My 16-year-old daughter was so overwhelmed with it all, she said she was going down to Perth prison with a brick in her handbag and batter the lot of them. Because she didn't want anything happening to her dad.

"In the end I begged him to stop doing it because I couldn't stand the stress of it. I knew that he was putting himself in danger. But we got through it all."