Pantomime villain, political pawn, or key terrorist player?

The loose tile in the ceiling of the Finsbury Park mosque, close to the office of its lead preacher, Abu Hamza, went unnoticed by all but a knowing handful of its worshippers.

It was not until a police search team prodded the tile on 20 January 2003 that its secret was revealed - the space behind it contained several dozen forged and stolen passports, credit cards and driving licences.

Elsewhere in the building, officers uncovered more identity documents and a stash of "training equipment" - chemical warfare suits, blank-firing pistols, knives and handcuffs.

The raid which led to the closure of the north London mosque marked the end of Abu Hamza's control of what anti-terrorism officers believe was a hub for Islamic extremists. The details of what was found at the mosque have not been disclosed by Scotland Yard until this week to avoid prejudicing the trials of Abu Hamza and Kamel Bourgass, the Algerian al-Qa'ida suspect convicted of a plot to carry out a ricin attack in Britain. It was a search of a flat rented by Bourgass in the Wood Green area of north London, intended to be used as a laboratory for ricin, that led police to the angular brick and concrete mosque in Finsbury Park. Among the items found during the ricin investigation at another address was a tape of Abu Hamza's sermons, exhorting Muslims to suicide attacks "on your doorstep".

Police investigating the 47-year-old cleric argue that the man whose rhetoric was characterised by the prosecution in his trial as that of a "recruiting sergeant for terrorism and murder" could not have been unaware of the criminal activities going on around him.

A senior police source said: "Many investigations into extremist networks have found ... links or connections to Finsbury Park mosque. I don't think it's a coincidence that so many terrorist investigations have led us to that building."

Abu Hamza was jailed yesterday at the Old Bailey for seven years. If and when he is deemed to have served his term in Britain, he faces extradition to America on 11 charges, including involvement in the kidnapping and murder of Westerners in Yemen. Abu Hamza, who faces a sentence of up to 100 years if convicted, denies the allegations.

Although questions remain about the relevance to global terrorism of the Egyptian-born cleric - an Islamophobic godsend complete with hooks for hands and a missing eye - the poisonous nature of his sermons is beyond doubt. From demanding the murder of Jews to exalting suicide bombing, this was a man with all the moral subtlety of a pantomime villain who spread the invective of a racist bigot.

But close scrutiny of him reveals a number of contradictions, ranging from his early life as a music-loving student to the extent of his involvement in the plotting that went on in the unkempt basement rooms of Finsbury Park mosque.

Zacarias Moussaoui, the French-Algerian student who is alleged to have been selected as the "20th hijacker" for the 11 September attacks on America, worshipped at Finsbury Park. So too did Djamel Beghal, the alleged operational commander of al-Qa'ida in Europe; Richard Reid, the Muslim convert who tried to ignite a shoe bomb on a transatlantic jet in 2001; Nizar Trabelsi, a Tunisian former professional footballer with drug problems who plotted a suicide mission against the US embassy in Paris; and James Ujaama, an American convert who ran the mosque's website in 1999 and whose evidence against Abu Hamza forms the basis for the extradition case being brought by the US.

But British detectives say privately there are no proven connections between the cleric and these plots. His trial heard that the nearest thing to evidence of an active plot was a mention of Big Ben - along with the Eiffel Tower and the Statue of Liberty - as potential targets in a so-called terrorism manual found at his London home.

Before his arrest in 2004, Abu Hamza presented two faces to his adopted country. When police arrived at his terraced house in Shepherds' Bush, at 3am two years ago, with an extradition warrant, their attention was drawn to two items in the sitting room. On a bookshelf and written in Arabic script was the Encyclopedia of Afghani Jihad - an 11-volume tome described by detectives as a "manual of terrorism".

The second was a framed certificate attesting to the holder's membership of the Institution of Civil Engineers in Whitehall.

The focus at the Old Bailey trial was on the encyclopedia, which formed the basis of a charge of possessing an item likely to be useful to a terrorist. Based on CIA training manuals provided to mujahedin fighters in the 1980s, the tome was described by the cleric as a gift. But the engineering qualification reveals much about the transformation of Abu Hamza.

The son of an Egyptian army officer, Abu Hamza was born Mostafa Kamel in Alexandria to a comfortable and largely secular life. The young man who stepped off a plane from Cairo at Heathrow in 1979 was far from the portly cleric who two decades later urged the murder of Jews and likened Britain to a lavatory.

Two years ago, Abu Hamza said: "I dreamt of coming to the West. I thought the West was a paradise where you could do everything you wanted. I was not a good Muslim." The young Mustafa Kamel was a trim keep-fit fanatic. He took a job as a receptionist in a west-London hotel to fund his studies at Brighton Polytechnic.

It was at this hotel that he met Valerie Traverso, a window dresser and divorced single mother from Chelsea. The couple married on 16 May 1980 at Westminster Register Office and she quickly became pregnant with Abu Hamza's son Mohammed.

He juggled his receptionist job with studies, and took work at a nightclub, where his duties included stints as a doorman. A classmate at Brighton Polytechnic, where he graduated in 1989, recalled: "He was buzzing with energy. He was a good-time guy - he liked to be liked. He was into rock music and karate. He was also a Chelsea fan. Mostly he was just a normal guy. Religion was nowhere on the radar - we were training to build office blocks and bridges."

Upon graduation, Abu Hamza paid his subscription to the Institute of Civil Engineers. His first job was overseeing work at Sandhurst Military Academy.

Perhaps due to the racist abuse experienced by his wife, it was at this time that Abu Hamza - and his Christian-born wife - began to show interest in Islam. At Valerie's behest, the couple began to study the Koran in the evenings. After the marriage ended in 1984, Abu Hamza intensified his education in the tenets of his faith, attending a mosque in Stratford, east London.

In the late 1980s, he changed his name to Abu Hamza al-Masri. He went to Afghanistan to join the fight against the Soviet occupation in 1991. He says that it was while clearing mines there that he lost his hands and left eye.

He returned to Britain after time in Bosnia as a preacher and by 1997 was leading prayers and meetings at the Finsbury Park mosque, and had remarried, to Nagat, 46. By 1998, Abu Hamza and his supporters had secured control of the mosque on a triangle of land in a traffic-choked corner of north London, and its funds.

Magnus Ranstrop, an al-Qa'ida expert from the Swedish National Defence College, said: "There is no doubt that what Abu Hamza did was to make the Finsbury Park mosque a magnet for people of extremist persuasions."

The Finsbury Park network

DJAMEL BEGHAL

An Algerian from Brixton, London. Security services say he is al-Qa'ida's operational commander in Europe and is alleged to have recruited suicide attackers at Finsbury Park mosque.

ZACARIAS MOUSSAOUI

The "20th hijacker" of the 9/11 attacks attended the mosque from 1998 to 2000. He may now receive the death sentence in the US.

RICHARD REID

The Anglo-Jamaican convert to Islam was supposedly recruited by Beghal. He was jailed for life in the US after trying to blow up a jet in 2002 with plastic explosive in his shoes.

NIZAR TRABELSI

Former footballer visited mosque with Reid and is likely to have been recruited by Beghal. Convicted of a plot to blow up a Nato base in Belgium and may have been planninga suicide attack in Paris in 2001.

JAMES UJAAMA

Abu Hamza gave him the role of running the mosque website. The white American convert provided US authorities with evidence against the cleric over a terrorist camp in Oregon.

FEROZ ABASSI

The student from Croydon was sent to an al-Qa'ida training camp in Afghanistan in 2000 at the behest of Abu Hamza. He was held at Guantanamo Bay.

ABU QATADA

Palestinian-born cleric who ran a mosque in Baker Street attended by Reid, Trabelsi, Moussaoui and othersin 1998. Abu Qatada has been described al-Qa'ida's ambassador in Europe.