MI5 opened a file on Jeremy Corbyn amid concerns over his links to the IRA, the Telegraph has discovered.
The Labour leader was investigated over fears that he could have been a threat to national security at a time when he was supporting convicted terrorists and campaigning for a unified Ireland.
The revelations come as a Telegraph investigation reveals Mr Corbyn’s full links to the IRA, including his support for one of the Balcombe Street gang, who waged a 14-month bombing campaign across south-east England, and his links to the bomb maker believed to have been behind the Hyde Park and Regents Park devices.
Mr Corbyn also shared a platform with a wanted IRA killer and John McDonnell, his shadow Chancellor, claimed that the pair of them used to “pin people against the wall” in the House of Commons to lobby them on behalf of Ireland, can be disclosed.
It was against the background of his support for the Republican cause that MI5 began looking into Mr Corbyn’s activities, and a source close to the investigation confirmed a file had been opened on him by the early 1990s.
They told the Telegraph: "If there was a file on someone, it meant they had come to notice. We opened a temporary file and did a preliminary investigation. It was then decided whether we should open a permanent file on them".
A file would be opened on "someone who sympathises with a certain group, or is friends with a specific person" and the purpose was to “assess whether the person was a threat", the source added.
The Metropolitan Police’s Special Branch was also monitoring the Labour leader at around the same time, but it is unclear if the intelligence was shared.
Peter Francis, the undercover officer turned whistle-blower, has revealed that the force secretly compiled files on Mr Corbyn and nine other MPs which detailed their political beliefs, personal background and any demonstrations that they attended.
He was personally asked to collect information on the Islington North MP as he infiltrated anti-racist groups in the 1990s, he said.
Conservative peer Lord Tebbit said: “I think it just marks him out as what he clearly is: a hard-Left, Marxist, terrorist sympathiser. It leaves him very comfortable in the company of McDonnell, who, as we know, said that they will gain power not through Parliament but on the streets and the picket lines.”
The former Tory chairman, whose wife Margaret was left permanently disabled by the 1984 bombing of the Brighton's Grand Hotel, added: “It’s a comfort to know that they were indeed being monitored, although clearly they stayed just on the right side, for them, of being charged with any offences. It just makes me feel that Mrs May is being perhaps unnecessarily indulgent towards the Labour party in order to win this election.”
It has also been claimed that the London Labour Briefing, a magazine which Mr Corbyn sat on the board of and frequently contributed to along with Mr McDonnell and Diane Abbott, was being monitored by the security services.
One reader purporting to be an MI5 worker wrote to the magazine on its 25th anniversary claiming that it has been their job for 25 years to monitor the publication.
Mr Corbyn has been questioned over his links to Republicans and during his leadership campaign refused five times during a BBC interview to condemn IRA murders.
A spokesman for Mr Corbyn said: "MI5 kept files on many peace and Labour movement campaigners at the time, including anti-Apartheid activists and trade unionists".
The Balcombe Street Gang and Corbyn's long association with the IRA
It was one of the IRA’s most notorious units whose bloody bombing campaign was only brought to an end during a five-day siege broadcast live on TV and watched by millions.
But until now it has not been known that a member of the Balcombe Street Gang found support from Jeremy Corbyn, who campaigned on his behalf as he was serving 11 life sentences for his part in the killing of 16 people.
The revelation is part of a series of links between the Labour leader and the IRA during a long association uncovered by a Telegraph investigation.
At the height of the Troubles, Mr Corbyn was a regular face at Republican protest events and attended events honouring dead terrorists, it can be revealed.
On one such occasion it was reported in An Phoblacht, a monthly newspaper published by Sinn Fein, that he shared a platform with an IRA volunteer who was wanted over the killing of an SAS soldier and whose extradition had been requested by the British Government.
At another event commemorating Bloody Sunday, Shadow Chancellor John McDonnell is recorded in a Republican newspaper as bragging to crowds that in the Lobby of the House of Commons he and Mr Corbyn had “pinned people up against the wall and said ‘do you know what has happened in Ireland in your name?’”.
Perhaps the revelation which will raise most questions over his judgement is his support for Hugh Doherty, a member of the Balcombe Street gang who at the time was serving 11 life sentences.
As well as attending protests, in 1987 Mr Corbyn handed a petition to then-prime minister Margaret Thatcher demanding better visiting conditions for Doherty and his fellow IRA prisoner Nat Vella and “the immediate transfer of Irish political prisoners to prisons near their homes”.
The Balcombe Street gang, who were named after the London street on which they were arrested after a five-day siege, were responsible for 16 murders. During a 14-month campaign of terror across the south-east of England they carried out 50 bombings and shootings, including shooting dead the TV personality and co-founder of Guinness World Records, Ross McWhirter, after he offered a £50,000 reward for information that would lead to their capture. They were released as part of the Good Friday agreement in 1999.
Addressing rally with IRA murder suspect
Archives from Troops Out, a London-based Republican organisation backed by Mr Corbyn, show him supporting the cause of Dessie Ellis, who was sentenced to 10 years in prison on explosives charges in the 1980s.
Ellis, whose family Mr Corbyn spoke alongside, was convicted of possessing bomb power-time units for bombs, including those suspected of being used for the Hyde Park and Regent’s Park attacks.
It can also be revealed that he toured Ireland in the 1990s addressing rallies calling for withdrawal of the British.
An Phoblacht reported that at a Dublin rally he stood alongside Angelo Fusco - a wanted IRA man who was on the run after escaping during his trial for shooting dead an SAS officer – and claimed that the partition was the “greatest miscarriage of justice in the history of relations between Britain and Ireland."
At the time Corbyn was speaking alongside him in 1994, the British Government were demanding Fusco’s extradition from Irish Republic.
Inviting Republicans into Commons after Brighton bomb
His efforts to support Republicans did not go unnoticed, and archives show that he left fellow MPs and members of his own party “appalled” at his decisions to invite Irish Republicans into the Houses of Parliament soon after the Brighton bombing.
He was visited in the Commons by close personal friend Gerard McLochlainn, the former 'voice of Sinn Fein in London', who had recently released from prison for conspiracy to detonate explosives, and Linda Quigley, who had also been recently released from a sentence for IRA-related offences.
The pair attended just weeks after Mrs Thatcher was targeted in the Brighton bombing, which killed five, including a Conservative MP.
Though he was unrepentant, the archives of An Phoblacht reveal that his actions saw him called before chief whip Michael Cocks, who accused him of being “deeply insensitive” and later said that he was “appalled” at his actions.
In the wake of the bombing a leader article in the London Labour Briefing, the hard-Left magazine on which Mr Corbyn was general secretary of the editorial board, “reaffirmed its support for, and solidarity with, the Irish Republican movement.”
It added: “Let our ‘Iron Lady’ know this: those who live by the sword shall die by it. If she wants violence, then violence she will certainly get.”
Paying tribute to IRA gunmen
Mr Corbyn risked offending victims of the violence again in 1987 when he paid tribute to eight IRA gunmen who were shot dead in an SAS ambush, telling a meeting of the Wolfe Tone Society: "I'm happy to commemorate all those who died fighting for an independent Ireland."
Despite the criticism often levelled at him, Mr Corbyn remained steadfast in his support for Irish unity throughout his backbench career. One on picket outside the Westminster Office of Jim Prior in 1983 he justified his links claiming that the “large Irish population elected me with a clear Troops Out ticket”.
Such was his support he was arrested in 1986 for joining a protest outside the Old Bailey to “show solidarity” with terrorists including the Patrick Magee, who was later convicted of the Brighton bombing.
His actions also caused concern to the Royal Ulster Constabulary, who stopped and questioned him five times in one day during a 1999 visit, with Mr Corbyn later complaining to then IRA linked paper An Phoblacht: “On each occasion it has been very clear to me the police officers who've stopped me know exactly who I am and exactly why I am here.”
Refusing to condemn IRA murders
Supporters of Mr Corbyn have said his relationship with Republicans should be seen in the context of the peace talks that followed, with Chris Mullin, the former Home Office minister, describing him as “ahead of his time”.
Since he has taken over the leadership of the party Mr Corbyn has been much quieter on issues of unity in Ireland, but his past actions have continued to plague him.
In a telephone interview with the BBC during his leadership campaign he refused five times to condemn the murders by the IRA. Before the line went dead, he said: “I condemn what was done by the British Army as well as the other sides”.
A spokesman for Mr Corbyn said last night "Jeremy campaigned for peace in Northern Ireland. To do so, he campaigned for the rights of all to be respected and spoke to people on all sides of the conflict.
"Jeremy campaigned for fair trials and against miscarriages of justice, after a series of well publicised cases, such as the Guildford Four and the Birmingham Six."
The spokesman added: "John and Jeremy do not pin people to walls. This is clearly figurative language".