Never-before broadcast footage of the late Martin McGuinness showing children guns and at the preparation of a car bomb has been unearthed for a major new TV documentary.
There are also claims from a former senior Army officer that Ian Paisley helped fund a loyalist terror campaign in the 1960s.
The revelations about the late First and Deputy First ministers will be aired next week in the first episode of an eight-part series made by BBC Northern Ireland's Spotlight team.
They gained access to classified documents and tracked down ex-terrorists, survivors of shootings and bombings, and the first two British soldiers to arrive in Londonderry in August 1969.
The producers of Spotlight on the Troubles: A Secret History have included unseen film from 1972 of an IRA bomb team putting the finishing touches to a lethal car bomb which later blew up in the centre of Londonderry.
Martin McGuinness is clearly seen walking at the back of the car before it sets off for Shipquay Street with its deadly cargo.
Former IRA man Shane Paul O'Doherty, who is from Londonderry, adds authenticity to the identification of McGuinness by saying: "I'm certain that he's filmed at the end there walking across the back of the car. Nobody walks like him with a stoop in his back."
The documentary shows people running for cover after the blast in March 1972 and amid the wreckage the bomb car's number plate is the same as the one seen driving off from where the former Mid-Ulster MP had been.
The Spotlight team acquired the footage from an American documentary maker whom they do not identify. They say it has never been aired on television before.
The documentary also includes footage of McGuinness, who admitted that he was once a senior figure in the IRA, in Londonderry sitting in a car handling a rifle and a revolver as children as young as eight years old peer through the open window.
The fact that McGuinness, who would go on to shake the hand of the Queen and denounce dissident killers of a policeman as traitors, did what he was doing in the company of children will cause anger among his unionist critics.
The documentary also links McGuinness's former Executive colleague - and so-called Chuckle Brother - Ian Paisley with terrorism in Northern Ireland and the Republic.
In the mid-60s Paisley was leading a campaign of unionist opposition to the Northern Ireland prime minister Captain Terence O'Neill, who wanted to end discrimination against Catholics with a series of reforms.
Reporter Darragh MacIntyre reveals that while the Stormont government was, in public, downplaying the threat posed by Paisley, its 'secret assessment' - uncovered in documents in the Public Record Office - was very different
They show that O'Neill ordered the RUC to record Paisley's speeches and sermons with a view to prosecuting him for incitement.
Intelligence reports also linked a number of organisations including the UVF to Paisley, who always denied any associations with the loyalist men of violence who, in March 1969, started a bombing campaign which they knew would be initially blamed on republicans and they hoped would bring down O'Neill.
Among the targets were the Silent Valley reservoir near Kilkeel and the Annalong viaduct.
David Hancock, a retired senior Army officer who was part of the permanent garrison in Northern Ireland, tells the documentary that he never believed the bombings "had the footprint of the IRA".
The authorities suspected Paisley was involved.
Hancock says: "I was good friends with the district inspector [of the RUC] in Kilkeel and he showed me the evidence that they had of the involvement of money from Paisley into what was then called the UVF.
"My memory is very clear from what the district inspector told me was that Paisley had supplied the money that financed the Kilkeel explosions."
Spotlight says that one of the bombers, Samuel Stevenson, who was Paisley's bodyguard, met nationalist politician Austin Currie to warn him that loyalists were about to attack an electricity substation in Ballyshannon in Co Donegal.
Currie tells the programme that Stevenson, who said the bombings were supported by Paisley, named one of the gang who would be at Ballyshannon as Thomas McDowell from Kilkeel.
"McDowell electrocuted himself," says Currie.
The loyalist, who was wearing a coat with a UVF insignia, is buried in a Free Presbyterian churchyard where his headstone declares he was a member of one of Paisley's organisations, the Ulster Protestant Volunteers.
In an interview from the archives, Paisley says: "I can't be responsible for everyone who is a member of a church that I pastor or an organisation which I lead."
By April 1969, O'Neill, who had famously appeared on television just a few months earlier to warn that Ulster stood at the crossroads, had resigned.
Within a short time, the growth of the civil rights movement and the attacks on marches by police had changed the Northern Ireland landscape forever.
One of the civil rights pioneers, Eamonn Melaugh, tells the documentary that he welcomed the police violence which was seen by millions of TV viewers across the world, adding: "I said when our blood flows, Stormont goes."
Derry was later to capture global headlines with the Battle of the Bogside, a three-day running battle which raged between the RUC and nationalist rioters after a loyalist march.
Shortly afterwards the guns came out in Belfast and four people, including nine-year-old Patrick Rooney, were shot dead.
Patrick, who was in his home in Divis Flats, was killed by an RUC bullet.
The sectarian clashes and the rioting were so vicious and so widespread that the Stormont government called on Westminster to send in the troops to bolster the beleaguered RUC.
Soldiers Dave Moffett and Peter Blyth were among the first troops to arrive in Derry and returned to the city for the Spotlight programme, saying they had been welcomed in 1969 by nationalists who saw them as rescuers and gave them cups of tea and thanks.
On the Shankill, loyalists, furious at policing reforms, turned their weapons on the security forces and David Hancock says it was the first time that British soldiers had been attacked by terrorists carrying the Union Jack.
A policeman, Victor Arbuckle, was killed, the first RUC officer to die during the Troubles.
Two Protestants, Herbert Hawe and George Dickie, were shot dead in a gun battle with the Army, who first claimed that Hawe had a gun before alleging that he was a petrol bomber.
Hawe's sister May Elwood tells Spotlight: "He was well armed, wasn't he? He was shooting them and he was throwing petrol bombs at the same time. It was definitely murder."
On the other side of the divide, there were splits among republicans.
Spotlight discloses "for the first time" details of a secret meeting at a house they identify in Athlone in late 1969 when several dozen republicans decided to form the Provisional IRA.
Veteran IRA man Des Long, who was at the meeting, says: "We knew we had a huge job in front of us but we were quite prepared to do it."
The IRA drew up a three-point plan: to defend Catholic areas, to carry out retaliatory action, and to eventually wage an all-out war against the state. Back in Belfast, the honeymoon period for the Army ended in April 1970 with sustained attacks on the troops. The IRA shot two Protestant men in east Belfast during what they called the Battle of St Matthews, a Catholic church on the Newtownards Road.
The Army were later to declare a curfew on the Falls Road, a move which antagonised nationalist residents and which was later described as one of the biggest military mistakes of the Troubles.
Spotlight interviews Joe Clarke, one of the many young men who joined the IRA.
He says the attitude to the Army had been "if you're going to start messing us about, we'll start messing you about".
An IRA sniper claimed the Provos' first Army casualty in February 1971 in the New Lodge with the shooting of Gunner Robert Curtis. His widow Joan said in an old TV interview: "I thought it was a mistake. I said soldiers don't get shot in Northern Ireland."
But he was the first of many soldiers to die. In March 1971, three Scot squaddies were lured from a city centre bar and shot dead at Ligoniel.
Tommy Anderson, who was a colleague of the trio, tells Spotlight he cried at the funerals and he says the killings made soldiers "think they weren't just fighting the IRA, they were fighting the Catholic people".
The Troubles were intensifying and the new unionist prime minister Brian Faulkner introduced internment in August 1971. But Operation Demetrius, which rounded up 342 suspected republicans, served only to alienate nationalists even further.
Spotlight says that British military intelligence had been preparing for internment long before Faulkner's move and Joe Clarke was one of the 'hooded' men spirited away for nine days of interrogation on the north coast, which the European court later found had been cruel and inhumane but didn't constitute torture.
Spotlight shows a clip from an ITV programme that was banned by the Independent Television Commission in which the IRA's chief of staff, Sean Mac Stiofain, effectively declared all-out war.
The Army's most senior officer, Sir Michael Carver, wrote a secret memo in December 1971 urging London to curb the powers of the Stormont government and recommending that soldiers should engage in less provocative activity, particularly in Derry.
But the Army's actions didn't exactly match Sir Michael's words. The Parachute Regiment were condemned for how they responded to a protest march on Magilligan beach and the commander of another unit described them as "hooligans in uniform". The same soldiers were responsible for Bloody Sunday in Derry when 13 civil rights marchers were shot dead.
Former priest Denis Bradley, who was in the Bogside, tells Spotlight: "Bloody Sunday changed everything. The IRA couldn't handle the number of people that they were being offered to join the republican movement."
The IRA bombing campaign was stepped up and civilians were caught up in more and more attacks like the Abercorn restaurant atrocity.
The day after the aforementioned Shipquay Street bombing in Derry in March 1972, Faulkner was summoned to London to be told by prime minister Edward Health that Stormont would lose its security powers. The entire cabinet resigned.
Loyalists mobilised at Stormont to show their anger and the home affairs minister John Taylor, now Lord Kilclooney, who had narrowly avoided death in an Official IRA shooting, left hospital to join his erstwhile cabinet colleagues on the balcony.
"It was a massive demonstration of unionism, and unionism rejecting British rule," he tells Spotlight.
Joe Clarke says he mistakenly believed that the fall of Stormont was the beginning of the end of British rule. He says: "We thought we were going to get our united Ireland. But we're still looking for it."
Spotlight on the Troubles: A Secret History starts on Tuesday at 8.30pm on BBC One NI and BBC Four. Subsequent episodes will examine the activities of the IRA and loyalists, collusion and the intelligence war