Men plead guilty to planning bombings of targets including stock exchange, US embassy and Boris Johnson's home

An al-Qaida-inspired gang of terrorists has admitted plotting to bomb the London Stock Exchange and targeting Big Ben and Westminster Abbey, after an 11th-hour plea bargain in court.

A handwritten list included the names and addresses of the London mayor, Boris Johnson, two rabbis, the US embassy and the London Eye as potential targets to attack in the runup to Christmas 2010.

The group's alleged "linchpin" was Mohammed Chowdhury, a 21-year-old from east London, who pleaded guilty at Woolwich crown court to preparing to commit an act of terrorism.

He and eight other men from London, Cardiff and Stoke-on-Trent were due to face trial this week. At the last minute they admitted the terror plot, but denied the intention was to cause death or injury.

Undercover detectives had followed Chowdhury and his right-hand man, Shah Rahman, as they observed Big Ben, Westminster Abbey, the London Eye and the Houses of Parliament on 28 November 2010, during an extensive surveillance operation that eventually led to the arrest of the gang.

Chowdhury was told by the trial judge, Mr Justice Wilkie, that he could face a jail term of 13 and a half years, plus a five-year extended licence period.

The men, who had initially claimed that their meetings were part of an innocent plan to raise money for an Islamic project in Kashmir, were also said to have plotted attacks on pubs in the West Midlands. They were understood to be preparing to make a bomb and detonate it at the London Stock Exchange by pretending to be traders and planting explosives in the toilets in the hope that the building would catch fire.

The arrests were the result of one of the biggest and most comprehensive anti-terrorist investigations of recent years. The men were the subject of a surveillance operation led by MI5 which targeted their homes and cars, and undercover officers followed their movements as they were examining targets.

The plotters met through membership of various extremist Islamist groups and stayed in touch over the internet, through mobile phones and at specially arranged meetings ? held in parks in a bid to make surveillance difficult. It is understood that some of the Stoke group had been planning to travel to Pakistan to a training camp with the aim of developing a long-term plot, probably within the UK.

Chowdhury and Rahman from east London and the Cardiff contingent were regarded as more like self-starters who probably held radical views for a long time but had taken the next step after immersing themselves in the philosophy of Inspire magazine, which promotes the ideology of Anwar al-Awlaki who was al-Qaida's leader in the Arabian peninsula. The key message from the publication was "get out there and do it", said investigators. Investigators know that Inspire has encouraged lone-wolf behaviour in the past, and they were worried to see a group of individuals behaving like a "pack of wolves".

The nine had been due to face a five-month trial, but pleaded guilty as part of a Goodyear Direction, which allows a defendant to weigh up whether they should plead guilty depending on the sentences they are likely to face.

Chowdhury and Rahman could be out of prison in six years; they will be released automatically at the halfway point of their jail term and spend the remainder of time on licence. If they had gone to trial and been found guilty they would have been sentenced to about 20 years in jail.

The group ? to be sentenced next week ? were inspired by Anwar al-Awlaki, the US-born Islamist cleric who was al-Qaida's leader in the Arab peninsula until he was killed in a drone attack last September. Chowdhury and his followers collected messages sent out by Awlaki, who had masterminded a plot to send bombs disguised as printer cartridges to US synagogues on cargo planes. His plan failed when the packages were intercepted.

The men are understood to have followed instructions to copy Awlaki's mail bombs in an al-Qaida magazine published five days before their first meeting in November 2010. The publication, Inspire, detailed Awlaki's attempt to post the bombs to synagogues in October 2010.

Chowdhury and his co-defendants, Gurukanth Desai, 30, his brother, Abdul Miah, 25, Shah Rahman and Mohibur Rahman, were found with copies of the magazine as well as an earlier edition. Rahman was told he could expect a 12-year sentence with a five-year extended licence for preparing to commit an act of terrorism.

Andrew Edis, prosecuting, said: "The role of Inspire magazine and al-Awlaki and the fact they were carrying out a small but high-profile and spontaneous attack shows they were in fact implementing the published strategy of al-Qaida in the Arab peninsula."

The nine men were arrested on 30 December 2010 after months of surveillance by police ? led by anti-terror officers from the West Midlands force. They had first met face-to-face at Roath Park in Cardiff in November 2010, where they discussed their ideas.

Chowdhury was nicknamed JMB by his co-defendants ? after the banned terrorist group Jamaat ul-Mujahideen Bangladesh. He and the others moved on from their first meeting to testing out bomb recipes, which they referred to as "cooking". It is understood that Miah and Desai caused an explosion in the street at one of their meetings in Wales.

Chowdhury and Rahman are also understood to have built pipe bombs at Chowdhury's home in Poplar, east London. Two other members of the group were recorded by a police surveillance operation denying the Holocaust.

Addressing Chowdhury, the judge said: "The intention was that [the bomb] should cause terror, economic damage and property damage. There was, however, a serious risk that it should cause death and serious injury.

"It was intended that this should be carried out in the near future, however at the time of the arrest no materials had been obtained nor firm dates had been set.

"The detailed target had been developed during the indictment period; various other projects were also considered during this time."

Chowdhury, he said, was the linchpin. He had carried out significant research of the target and construction of the device, the judge said. With Rahman they "in due course became party to a plan to place a live explosive device in the stock exchange".

Chowdhury and Rahman had visited London landmarks including the London Eye and Westminster Abbey after a meeting with Miah and Desai on 28 November 2010. They were also seen examining the Palace of Westminster, Blackfriars Bridge and the Church of Scientology in London.

Henry Blaxland QC, defending Chowdhury, however, said the basis of his guilty plea was that it quite specifically involved "no intention to cause death or injury".

Chowdhury, Rahman, Usman Khan, 20, of Stoke, Nazam Hussein and Mohammed Shahjahan, both also from Stoke, Miah and Desai, both from Cardiff, all admitted engaging in conduct in preparation for acts of terrorism, contrary to section 5(1) of the Terrorism Act 2006.

Mohibur Rahman, from Stoke, admitted possession of an article for a terrorist purpose; namely, copies of Inspire magazine from summer 2010 and autumn 2010.

Omar Latif, 28, from Cardiff, admitted assisting others to engage in preparation for acts of terroris
m by travelling to and attending meetings on 7 November and 12 December 2010. All nine defendants denied conspiring to cause an explosion or explosions of a nature likely to endanger life or cause serious injury to property.

Chowdhury, Shah Rahman, Latif, Desai and Miah further denied possessing a document or record containing information of a kind likely to be useful to a person committing or preparing for an act of terrorism. They will be sentenced next week.