Some of these “dissident republicans” had already helped to form the so-called New IRA, which has admitted responsibility for the death in April this year of the young journalist Lyra McKee, who was shot by a sniper during an apparently staged-for-TV riot in Derry. Doherty has a bit to say about that, too.

Paul Doherty is a cheery man. He’s thickset and stocky and likes to make jokes – can’t help himself, really – and runs perhaps the least romantically named travel business in the world, Bogside History Tours. It takes a surprisingly large number of visitors (between two and 40 per tour) on twice-daily guided walks through Derry to the Bogside, a neighbourhood in the city’s west, where the ghosts of Bloody Sunday’s dead still march alongside his father, on murals the size of houses.

Paul’s younger brother, Gleann Doherty, is leading the walk on the morning I arrive, and Paul offers me a more exclusive “taxi tour”. It begins with an eccentric industrial history of Derry, whose docks were established before the famous shipyards of Belfast, where the passenger liner RMS Titanic was constructed by a largely Protestant workforce.

“The most celebrated ship in the world, the Titanic, never completed a journey,” says Doherty. “People say, ‘Why did it never complete a journey?’

Doherty talks about the 17th-century Plantation of Ulster, in which Protestants from England and Scotland, who were loyal to the British Crown (“loyalists”) were settled in the north of Catholic Ireland, usurping Irish landowners and ultimately exercising political power through gerrymandered voting and a system which, until 1968, allowed (largely Protestant) business owners an extra vote in local elections while (often Catholic) renters had no local vote at all.

We drive over Craigavon Bridge, named for James Craig, the first PM of Northern Ireland and founder in 1912 of the Ulster Volunteer Force – “A modern-day terrorist and drug-racketeering operation; beside that, they’re okay,” says Doherty – to a lookout over a walled city of cathedral spires, council houses and dozens of boxy, repurposed shirt factories. We motor down from the hills and back into town, where Doherty’s taxi cruises the close, stony streets, stopping at corners that paid witness to the events that led to the death of his father: the rise of the Northern Ireland Civil Rights Association (NICRA) whose demands included an end to anti-Catholic discrimination; one man, one vote; and the reform of the heavily Protestant Royal Ulster Constabulary (RUC), the country’s then police force.

Peaceful civil rights demonstrations were attacked by loyalists and the RUC with increasing degrees of violence until January 1969 when, in the aftermath of a march from Belfast to Derry, the RUC rioted in the Bogside, assaulting Catholics in the streets and in their homes. Residents put up barricades and declared themselves citizens of Free Derry and outside the authority of the police. In August, a much larger riot – the “Battle of the Bogside” – saw the police expelled from Free Derry by locals throwing petrol bombs, and nationalists and loyalists fighting hand-to-hand in the streets of the city they shared.

An end-terrace house, which had become famous internationally when its side wall was painted with the slogan “You are now entering Free Derry”, still stands as Free Derry Corner in the Bogside, although the other homes in the terrace have been demolished. “They were gonna redevelop the Bogside and build a roadway,” says Doherty. “They were gonna move the [Free Derry] wall and take the wall away, but the negotiations were very skilful: ‘Touch the wall and you’re gonna be disappeared yourself.’ So that was the end of that.”

I grew up in England in the 1970s, near the base of the Parachute Regiment. When I arrived in Northern Ireland recently, I was puzzled to see what looked like the regiment’s flag flying in parts of Belfast. I thought the outspread wings must stand for something else on this side of the Irish Sea. They don’t. Doherty says the flag was also raised a few weeks ago in The Fountain estate, a loyalist enclave near the heart of Derry, “in support of Soldier F”. (Soldier F is the man who shot Doherty’s father.)

“The people who want to do it must have sick minds,” he says. “In 2019, 400 yards [370 metres] from where the massacre of Bloody Sunday happened, these people feel the need to fly the flag of the Parachute Regiment, celebrating the murder of 14 innocent people in the Bogside in 1972.” To Doherty, it’s as if his neighbours are celebrating the killing. “There’s negotiations at the minute to bring [the flag] down,” he says. “The negotiations were begun by ourselves – the [Bloody Sunday] families – through our member of parliament and the loyalist terror and paramilitary groups here. They don’t seem to be working. So if you hear it was taken down in the middle of the night, by some guy on a ladder, it’ll be me that did it. And I mean that sincerely.”

It’s a very short drive to The Fountain, where every lamppost is painted red, white and blue, and the Paras’ flag hangs limp on a windless morning. Doherty scowls. “That’s hurtful,” he says. “It’s wrong. It degrades this community. So I’m just going to see what type of ladder we’ll need.” Mentally, he measures the distance between the banner and the ground. “We’ll need a 16- or 18-foot ladder,” he decides, eventually. “We’ll go up and get that down.”

Doherty does not believe anyone could truly support Soldier F, if they knew the facts. “I’ll tell you what Soldier F did in the Bogside …”

On Sunday January 30, 1972, the NICRA held a march through Derry, even though all marches and parades had been banned. In the month before, two RUC had been killed in Derry, and the British Army believed the planned demonstration would provide cover for the IRA. The 1st Battalion Parachute Regiment was brought in to Derry to police the demonstration and arrest rioters. They ended up shooting 28 Catholic civilians, of whom 14 were killed, 13 on the day and one later. A British tribunal set up in the immediate aftermath of the killings found that the Paras had been fired upon first, and largely accepted claims that the dead marchers were gunmen and nail bombers. The families of the dead refused to accept the findings and for decades argued that peaceful protesters had been massacred.

In 1998, in the wake of the Good Friday Agreement, the British government established the Saville Inquiry, which culminated 12 years later with a 10-volume, 5000-page report. Saville found that the Paras had shot first and without warning; their victims had been all but unarmed and helpless, and posed no significant threat; that the IRA had maintained only a small, shadowy presence and loosed off a few ineffective shots; and that the Paras had lied.

It is this story, more or less, that Doherty tells at the Creggan estate among the heavily muralised roads around Free Derry Corner. While the area remains a working-class Catholic republican stronghold, the streetscape has changed: buildings have been demolished, whole blocks torn down. Doherty reaches into the past, to point to where things used to be, as he describes the last moments in the life of his father, Patrick Doherty, a 31-year-old plumber’s mate and member of NICRA, who joined the march from the Creggan.

The protesters set off mid-afternoon and were diverted from their chosen route by army barricades. Angry youths threw stones at the soldiers, who replied with tear gas and water cannons. The march organisers redirected the rally towards Free Derry Corner, and a group of soldiers fired live rounds in the direction of the rioters. Wounded men began to fall. Two civilians were knocked down by armoured cars. Soldiers broke through their own barriers to arrest the stone-throwers.

As the firing continued, the marchers ran for cover. There were already seven dead when Patrick Doherty sought safety around a small square named Glenfada Park, where today stand his son, Paul, and I. As the death toll mounted, the Paras’ brigade headquarters ordered the soldiers to cease fire. A radio operator – now dubbed Soldier 027 – passed on the order to men known at the Saville Inquiry as Soldiers E, F, G and H, but they ignored the command and set about hunting down and killing Catholics. “In here,” says Doherty, “in Glenfada Park they murdered four.”

He knows the ground where each man fell. “William McKinney was in a crowd running from here, across here,” says Doherty. “He was trying to escape right over here. And Soldier F, disobeying orders, went up that street, and he murdered William McKinney about here. Willy was shot in the back. The bullet raced through his body and went into the body of a teenager called Joseph Mahon. Joseph Mahon played dead when Soldier F touched him with a rifle to his head. Soldier F walked away thinking he’d killed him, and he shot Jim Wray in the back. Jim Wray hit the ground with such force that he didn’t get his hands in front of him.

“Soldier G walks towards him,” he continues. “Jim Wray was shouting, ‘Somebody help me! I can’t move my legs! Somebody help me!’ and G shoots him in the back again, executes him, then turns to his friend and says, ‘There, I got another one.’

“And F came out,” says Doherty, “knelt down at that lamppost right there and murdered my dad.”

Patrick Doherty was shot from behind as he tried to crawl away. A bullet drove into his buttock and ripped out of his chest. On its way through his body, it lacerated his aorta, diaphragm and left lung, tore his colon and bowel attachments, and fractured two of his ribs. “Soldier F knelt down there,” says Doherty, “observed by hundreds of people, killing my dad, and then very clearly watching a man walking towards him with a white handkerchief in his hand. Barney [Bernard] McGuigan said to him, ‘Don’t shoot’ and Soldier F shot him.”

There were six children in the Doherty family. Paul was eight years old. “We were home,” he says. “With my brother and my friends, we were all outside playing marbles. Our home suddenly filled up with people, and then a young guy came up and joined in with the marbles for about 10 minutes and said, ‘Oh, by the way, your dad’s dead. I seen him get taken into an ambulance over here.’ And my mum then came and told us he was killed.”

I have to ask Doherty how their lives changed, although I know it’s a stupid question. “It is,” he agrees, as is his way. “The death of a parent’s one thing, the murder of a parent’s another thing. I wouldn’t like to relive that in the heart of a child. We sort of individualised ourselves as a family. My mum was on medication. My sister had to really look after the two [youngest] children. And we all had to adapt to a different type of life. My dad was very regimentist [sic]. We had to do certain chores every morning: somebody had to do the dishes and somebody had to shine the shoes. It was a good way of being brought up. The discipline – that all went out the window. Education went out the window as well.”

Their loss affected them each in different ways. Doherty’s older brother, Tony, joined the IRA and spent four years in prison. Today, Tony’s the author of two well-received, lyrical memoirs. There was turmoil for all the children but, “We’re all very successful in what we’re doing now,” says Doherty.

Most of the Saville Inquiry’s hearings were held in Derry but certain witnesses, including Soldier F, were permitted to testify in London. Doherty travelled to London with his family and watched Soldier F on the stand. What was it like, ask I – the master of the dullard’s query – to be in the same room as his father’s killer? “Aye, it was strange,” says Doherty. “I can’t describe it. It just put a face to an armed thug who had no care for himself or his community he came from, and he came into this community and just shot it to bits.”

Soldier F confessed to nothing but a poor memory. Five hundred and seventy times, according to Doherty, he answered questions with “I can’t recall”. But Soldier 027 – speaking from behind a screen to protect him from being identified – said the soldiers had killed innocent people for no operational reason, and called their actions “unspeakable”. Soldier 027 had been trying to confess for years. “We were getting telephone calls in the late 1980s from a soldier who was crying down the phone,” says Doherty. “He left the Army, hit the drink, and then he told the truth.” As for Soldier F, “If there was any kind of remorse, you would have to deal with that, but there was no remorse at all. And, again, forgiveness – you can’t forgive anybody who doesn’t ask for it. They shouldn’t get it.”

Did Soldier F know who Doherty was? “He would’ve been made aware of who we were,” says Doherty. “I’m not sure if he would’ve individualised us. We gave him a wee stare every time he went past us, so he probably would have. He was 53, he’s got a tan, athletic, small, stocky. He looked like he looked after himself. He has a very light-spoken voice. But obviously he had killing in his DNA.”

Saville found Soldier F had shot dead Patrick Doherty and Bernard McGuigan – but, under the terms of the inquiry, any evidence heard was inadmissible in any subsequent prosecution. A separate police investigation led to Soldier F being charged in May only with the murders of James Wray and William McKinney and the attempted murders of four others.

The families are bitter that only one man, Soldier F – a lance corporal – will be charged over Bloody Sunday. In the years since the massacre, Soldiers E and G have died, and the Northern Ireland Public Prosecution Service has said there is insufficient admissible evidence to provide a reasonable prospect of convicting other soldiers: dead bodies are not enough.

“We’ve heard since that the Public Prosecution Service were split on whether they should charge anybody,” says Doherty. “So we think they gave us a token. We wanted the remaining soldiers charged in a joint enterprise. We wanted the officers – some of whom are still alive – but you don’t get that.”

The case is scheduled to begin this month in the imposing, neoclassical Bishop Street courthouse, which Doherty identifies as the most bombed building in Derry. In January, Doherty pointed this out to four young Dutch women on a taxi tour. “And the next thing, it was blown up by the New IRA,” says Doherty. “I met them down the street, and I said, ‘Aye, it was blown up last night.’ ”

The most recent bomb caused little damage, and the New IRA are seen by many republicans as bumbling clowns who cannot even blow up a courthouse. But the joke turned acrid, as Irish jokes are wont to do, when a New IRA sniper shot dead the highly regarded Lyra McKee, a working-class Catholic journalist and LGBT activist, during a riot that Doherty says was staged for a TV crew. Apparently, McKee was not targeted as a journalist. She was simply standing too close to a police van. The New IRA admitted responsibility and apologised.

“The statement that they came out with then, trying to defend this, was adding insult to injury: that the girl was ‘standing behind enemy lines’ and ‘ground forces’ and this. That’s a relic from the past. They will say, ‘Well, the IRA did this type of thing as well.’ Well, we can’t argue that for ever and ever. Sometimes you’ve got to say, ‘There was a time for war and a time for peace.’ But the dissidents have no support, they’ve got no strategy, they won’t debate with anybody, they won’t talk to anyone, and they get young guys into the ranks of their organisation and tell them they could be heroes for Ireland.

“Well,” says Doherty, “the heroes for Ireland are all lined up in the cemetery.”

Police have arrested four suspects for the shooting of McKee, including a 15-year-old boy.

The demonstrators who died on Bloody Sunday were never forgotten. In some ways, their memory has grown larger over the years. Huge murals in the Creggan, painted between 1996 and 2008, bear their portraits and those of the men who braved bullets to rush to help them. “These people were heroes,” says Doherty, “because they could’ve jumped over them, ran away, but they didn’t. They stayed with them. They comforted them until they died. The guy who helped my dad until he died was called Paddy Walsh – he crawled out to my dad, the bullets were flying over his head as he stayed with him.”

On display in the nearby Museum of Free Derry is a famous photograph of Paddy Walsh crawling over to the corpse of Patrick Doherty. It looks as if Walsh has lent his own head to Doherty’s broken body. A simple monument and garden dedicated to the victims of Bloody Sunday stands close to the museum.

“The garden was paid for by lawyers and barristers for the families,” says Doherty. “We asked them for money – and they were making plenty of money – so they gave us the money to do this garden. It’s lovely. Mostly old neighbours used to look after it, but most of them are dead now, so now and then we come over ourselves and do a bit of weeding.”

This isn’t my story – far from it. I’m just a journalist who asks stupid questions, tramples on hearts, trespasses on grief. But I went to school in Aldershot, England, the home of the British Army and – in those days – the base of the Parachute Regiment. We moved to the town because it was cheap, because nobody wanted to live alongside the Army. It was in Aldershot that the IRA planned to extract revenge for Bloody Sunday with a bomb attack on the officers’ mess of 16 Parachute Brigade. The attack was supposed to kill and maim the men – or perhaps just the kind of men – who ordered their troops to open fire in the Bogside.

Instead, a time bomb in a stolen car exploded outside the building at 12.40pm on February 22, 1972 and tore apart the bodies of a Catholic British Army chaplain, a civilian gardener, and five local women variously described as kitchen workers, waitresses and cleaners. One of the women was the mother of a boy who was eight years old – the same age as Paul Doherty on Bloody Sunday. There was so little left of her that she could not immediately be recognised from her remains. Eventually, she was identified by a tattoo.

I moved to Aldershot three years after that attack. The disappeared woman’s son was in the year below me at school. I knew him very slightly. I never knowingly met any of the families of the other victims, but another boy whose mother was murdered that day – Karl Bosley – signed up with the Paras (“with anger and hatred in my heart,” he said later) – just as Tony Doherty joined the IRA. Apparently, Bosley was not permitted to serve with the regiment in Northern Ireland.

The Troubles in Northern Ireland continued throughout my schooling, and the Paras were a fierce and terrible presence in the town. They departed for tours of the province and returned with fury in their eyes, prowling the streets like the jungle cats tattooed on their hamhock forearms, at war with the world. And, of course, some of them never made it back. In an ambush near Warrenpoint in County Down in August 1979, the IRA killed 18 British soldiers, 16 of them Paras.

In Aldershot, the survivors policed their own pubs. Most of the town centre was a no-go area for civilians, and the Paras’ pubs around the high street were “airborne” only. Even other soldiers – “crap hats” – copped a kicking if they walked into the Pegasus, the Queen or the Trafalgar. You wouldn’t send the Paras overseas to police a demonstration. You’d dispatch them to destroy it. There are no pictures of the body of the eight-year-old’s mum, because there was nothing left to photograph. A small memorial at the site of the bombing is hardly visited by people outside the families, and when I went back to Aldershot a couple of years ago, I couldn’t even find it. Apparently, the area is going to be redeveloped, and the new houses will look down upon a memorial garden.

While the Irish may have long memories, it sometimes seems as if the English remember nothing at all. There are no tours to retrace the last journeys of the cleaners, as they came from the council estates to the garrison to work for a wage. And there is fierce feeling in England today that men like Soldier F should be left alone, that the post-Good Friday justice system let many imprisoned IRA “volunteers” off the hook and the same courtesy should be due to every British soldier – although the provisions of the agreement specifically excluded the perpetrators of crimes that had not yet been prosecuted.