Two men, two very different places, all connected by one country - Libya.

It was back in 2007 that I met Sir Mark Allen. He was introduced to me by one of the organisers of the annual book festival at which he was appearing in the small Scottish town of Wigtown.

To this day I still have a signed copy of Allen’s acclaimed book, ‘Arabs.’

One of Britain’s leading Arabists, it was only a few years earlier in 2004 that Allen lost out to Sir John Scarlett in his bid to become head of the British intelligence service, MI6.

Little did I know it back in 2007 but just four years later I would meet another man in a very different place that is inextricably connected to Sir Mark Allen and events featured in news headlines throughout the week.

That place was Libya’s infamous Abu Salim prison in the heart of the country’s capital, Tripoli.

The man was a gentle, quiet spoken Libyan called Ahmed Albousifi.

A long time ago back in January 1989 Albousifi was listening to jazz music in his car on the way to work at a Libyan airport handling company where he was as an IT manager. That morning he made a deliberate detour along Tripoli’s corniche so he could catch a glimpse of the sunlight on the wide-open expanse of the sea.

In all, he says, that morning reminded him of why people “insist on life in spite of all its sorrows and troubles”.

What Albousifi didn’t know then was that for a long time to come he would never set eyes on his family again. He would also never know why, that morning, two armed secret policemen came to his office, insisting they only wanted to talk to him for 10 minutes.

Ten short minutes that would turn into 10 years of living hell inside Abu Salim prison, Libya’s most dreaded jail under the dictatorship of Colonel Muammar Gaddafi. Abu Salim is to Libya what Abu Ghraib was to Iraq, but Ahmed Albousifi was no terrorist.

“Maybe I was turned in for money, Gaddafi’s informers and followers were paid 10 dinars for every name they brought. It was a way of life for some people,” Albousifi told me when I interviewed him in 2011 just days after Gaddafi was overthrown during the Libyan revolution and Abu Salim prison was liberated.

Whatever the reason for his arrest, blindfolded and handcuffed, Albousifi was driven to Abu Salim, only to find that even the prison administrator was perplexed by his presence.

“I have only your name, no other information,” he admitted. But such things mattered little once you were brought through the gates of the hellhole that was Abu Salim.

Many others were brought here too, among them Libyan dissidents like Abdel Hakim Belhaj and Sami al-Saadi, who last week were back in the headlines.

In 2004 Belhaj and al-Saadi along with their families were abducted and flown by the CIA from Bangkok and Hong Kong to a secret prison before being transferred to Abu Salim where they would spend the next seven years.

Both men were arrested as part of the now infamous rendition programme involving the CIA and MI6 before being tortured during their detention.

Belhaj was later to tell of how “very surprised” he was that that British intelligence officers were among the first to interrogate him in Libya.

“I wasn't allowed a bath for three years and I didn't see the sun for one year.

“They hung me from the wall and kept me in an isolation cell. I was regularly tortured,” he would later recount.

Last week after more than four years of Scotland Yard investigations, and months of agonising within the Crown Prosecution Service (CPS) it was decided that there was insufficient evidence to convict any British minister or intelligence officers, among them former chief MI6 officer Sir Mark Allen.

Prosecutors however did conclude that Allen had been in contact with countries that detained Belhaj and al-Saadi in 2004 as they were transferred back to Gaddafi’s Libya and had “sought political authority for some of his actions”.

Belhadj and al-Saadi were handed over to Gaddafi’s henchmen in the same year that Tony Blair struck his notorious ‘deal in the desert’ with the Libyan despot.

Evidence of MI6 involvement in the Libyans’ rendition first came to light by chance when a cache of documents was discovered in the bombed-out offices of the Libyan security services after the Gaddafi regime fell in 2011.

In one jaunty letter to his Libyan intelligence counterpart Moussa Koussa, Allen trumpeted MI6’s role in the operation.

“I congratulate you on the safe arrival of Abu Abd Allah Sadiq [another name for Belhaj]. This is the least we could do for you and for Libya to demonstrate the remarkable relationship we have built over recent years,” Allen wrote.

After the Allen letter came to light, Tony Blair said he had “no recollection at all” of the Libyan rendition. Jack Straw, then foreign secretary responsible for MI6, told MPs in 2005 - a year after the Libyan abductions - that “there is simply no truth in the claims that Britain has been involved in rendition full stop.”

But after the Allen letter emerged, Straw changed tack saying, “no foreign secretary can know all the details of what its intelligence agencies are doing at any one time.”

The brutal ordeal that Belhaj and al-Saadi underwent in Abu Salim while significant in terms of foreign intelligence service involvement was not uncommon for many of the prisoners brought there.

Ahmed Albousifi to this day still doesn’t know why he was taken to the prison, but he too was tortured during those ten interminable years he spent in Abu Salim.

When we met during those turbulent days in Tripoli back in 2011, fighting still raged around the city. As one of the first western journalists to enter the newly liberated Abu Salim I was to see first hand and hear accounts of the horrendous conditions under which ordinary prisoners like Albousifi and ‘special cases’ like Belhaj and al-Saadi were kept.

As with all new arrivals, there was the prospect of the “wake-up party” as jailers called the beating that prisoners were subjected to from the moment they were dragged out of initial interrogation until thrown into a cell. That cell, the first Albousifi was to inhabit for the whole of the next year like Belhaj, sat in almost total darkness.

“From sunrise till sunset it was impossible to see the fingers held up in front of your face,” Albousifi recalled, before describing the other horrors this place held.

“It was right next to the torturing room, and I spent about four months, perhaps, only sleeping an hour or two a day because of the screams that came from there.”

Inside Albousifi’s cell was a small vent that he says was no more than 12cm by 50cm through which he could see. On the other side of this they hung up and tortured a man for 14 days.

“His arms were tied behind him and he was kept on his tip-toes the entire time to keep the pressure on his limbs, every three days they would pour cold water on him and beat him with electric cables. For six months afterwards the man couldn’t move his arms without excruciating pain, because of what they had done to him.”

By now Albousifi had been moved to another cell that he shared with between 18 and 20 other prisoners at any given time.

In this cramped, stifling environment the men were given only one litre of water a day each for drinking and washing. Often they would sleep without mattresses; tuberculosis, scabies and asthma were rife. Abu Salim however had much worse in store.

“The incident started on June 28, 1996, when the jailers came to distribute food,” Ahmed recalls. They would often taunt the prisoners by calling them “girls”. The Islamist activists among the prisoners, many of them members of the Libyan Islamic Fighting Group (LIFG), of which Belhaj and al-Saadi had been leaders, would rather have died than be the subject of such “insults,” Albousifi says.

As it was, most of these Islamist prisoners - along with many others that had no evident political or anti-Gaddafi allegiances - would be massacred in the following days in the single-biggest outrage of Gaddafi’s brutal 41-year reign.

That massacre would be carried out under the supervision of Abdullah Senussi, Colonel Gaddafi’s brother-in-law and the head of Libyan military intelligence who would be dubbed the “butcher of Abu Salim.”

On the morning of June 29, 1996, Albousifi heard powerful explosions and gunfire that went on for three solid hours. There were also cries of “Allahu Akbar” (“God is Great”) from inside the cellblocks as the men were killed. In all some 1270 men were massacred staying buried inside the grounds of Abu Salim for another two years before the regime brought trucks and a bulldozer to remove their remains.

As the investigation into MI6 involvement in the rendition of Belhaj and al-Saadi has revealed, Abu Salim’s past contains many dark secrets. In some instances there are those who have gone to great lengths to keep it that way.

On entering the newly liberated prison back in 2011, two colleagues and myself were to come across abandoned administrative buildings, the floors of which lay strewn with sack-loads of files marked SECRET.

What the files contained were Libyan Mukhabarat - security service - accounts of Abu Salim’s inmates. While most of the documents related to prisoners like Albousifi who were clearly the unwitting victims of the politically paranoid police state that Gaddafi ran, some were highly detailed files on Islamist and Jihadist activists, some of whom were members of the Libyan Islamic Fighting Group (LIFG), an organisation said to have links with al-Qaeda.

Disquieting as this was, it was the sinister events that happened later the same day that told of the extent to which people were running scared of Libya’s murky secrets. No sooner had we examined some of these confidential files than a group of menacing armed men arrived in pick-up trucks, making it clear we were not welcome and began to torch the stacks of documents.

To this day I still wonder who those mysterious gunmen were. That they had been tipped off about our presence was undoubted. At face value their bearing and attitude certainly bore the hallmarks of Islamist fighters. However, everything about them suggested they were well-trained, disciplined, professional soldiers who knew exactly what they were there to do - Arab special forces perhaps?

Returning to Abu Salim the following day, we discovered the heaps of files still smouldering, and one of our guides, another former Abu Salim inmate, said he was convinced the men were pro-Gaddafi fighters disguised as rebels who had come to get rid of embarrassing evidence of atrocities and human rights abuses committed by the former regime in Abu Salim.

Uncertainty remains as to who these gunmen really were, but across Tripoli at that time there was a mad rush to clean up the paper trail that might implicate former regime members, expose as yet unknown jihadists, or reveal the extent to which British and American intelligence agencies - MI6 and the CIA - were cosying up to Gaddafi’s regime in the hope of nailing a few terror suspects and Islamic extremists of their own.

Responding to the Crown Prosecution Service decision last week in the Belhaj and al-Saadi case, Cori Crider, a lawyer from the human rights organisation Reprieve who represented the two men said: “With today’s official acknowledgement that British officials were involved in this rendition, the fig leaf of official secrecy in this case is in tatters.”

Crider once again pointed out that Sir Mark Allen took credit, in writing, for the operation while “Jack Straw, we are told, signed it off.”

“Strangely, the CPS’s attitude to all this is ‘see no evil, hear no evil, and speak no evil’.

That evil was done in Abu Salim is however beyond doubt. For Ahmed Albousifi his experience of the jail scarred him irreparably. He says that sometimes his wife tries to talk to him about what happened, but it does no good.

“All these years after my release there is never a week passes without nightmares,” he told me. “In here, I’m still living inside Abu Salim,” he says, gently tapping the side of his head. “I always will be.”