He remembers them gathering on the streets of Derry, full of naïve optimism, their banners lighting up the dismal streets. 'One man, one vote', 'Jobs and houses', and 'End the Special Powers Act', they declared. They were a motley crew of students, housewives, workers and revolutionaries.

Those who knew the words were singing 'We Shall Overcome'. The civil rights marchers were chatting about which team would win the Irish league match at the Brandywell when the police laid into them. "They baton-charged us," says Willie Breslin. "Charlie Morrison, a bricklayer, was so badly beaten, he couldn't work for a month.

"Matt Harkin's back was a mess. A policeman made a go for my testicles but I raised my knee in time so he only got my thigh. Four police officers beat a wee man until he fell to the ground, then they picked him up and threw him over a wall. He suffered a broken leg and arm. But it didn't deter us.

"There were only 400 marching – far more people were at the Brandywell for the football. But when we held the same demonstration six weeks later, 20,000 were there. People were saying, 'We won't accept this, enough is enough.' They were giving two fingers, with both hands, to the government."

It's 40 years ago today since the Derry march which brought the blatant discrimination and oppression in the North to world attention. Civil rights leaders – Bernadette Devlin, Eamonn McCann, Ivan Cooper and Michael Farrell – became household names. Paddy Devlin and Gerry Fitt were already well-known politicians and others, like John Hume, became so.

But it was ordinary men and women who were the backbone of the movement. Even today, they remain the unsung heroes and heroines. Willie Breslin, a 28-year-old teacher on 5 October, 1968, describes himself as a "hod carrier" of the civil rights movement.

"Derry was 73% Catholic but it was run by unionists. There were 2,400 families on the housing list but in two years they built only 22 new homes. There was a policy to keep Catholics homeless or in rented accommodation because only householders had the vote in local government elections," Breslin says.

"The Wilson family lived in a caravan. They had no electricity, running water or toilet. Mrs Wilson gave birth to a baby who died eight hours later. The doctor blamed the awful living conditions. A group of us pulled the caravan onto the middle of the Lecky Road in protest.

"The police came and everybody was arrested except myself and another fellow. He was a civil servant and I was a teacher. Arresting us would have backfired: they wanted to give the impression that all the protestors were unemployed layabouts."

Dermy McClenaghan was a 26-year-old dental technician and Derry Labour Party member who helped John Hume carry some of those injured on 5 October into Cassoni's Italian restaurant. His civil rights passion was intense.

"We lived in horrendous conditions in the Bogside," he says. "Our house was riddled with damp and so badly wired that you got electric shock if you touched the wall. My father died of TB. I saw it as a family tragedy and as political – he wouldn't have died had we decent housing."

McClenaghan did what he could to help others who were living in slums or homeless. "I had my own housing list of the most desperate families. When I heard a house became available somewhere, I'd move a family in to squat. I'd an electrician, a joiner, a plumber, step-ladders and a bag of tools. We'd go along and do up the house to make it habitable."

Despite the seriousness of the campaign, McClenaghan also remembers the crack and camaraderie: "Jan Palach burned himself to death in Prague's Wenceslas Square in protest as Russian tanks rolled in. A man in Derry threatened to burn himself to death in Derry's Guildhall Square if he didn't get a decent house by a certain date. He was very hard to please. When the deadline day arrived, he woke up to find six cans of petrol placed by local people on his doorstep."

Wrong

Inez McCormack, a 21-year-old Protestant with strong security-force family connections, was an unlikely civil rights activist. "A cousin in the B Specials was shot dead during the IRA's border campaign. I had no active knowledge of meeting or speaking to a Catholic until I was a teenager. I had no sense anything was wrong with the place I lived," she says.

After finishing college in 1968, she spent the summer in London. There, she met and fell in love with Vinnie, a Derry Catholic and civil rights activist, and became involved in anti-Vietnam demonstrations. "After what happened the Derry marchers on 5 October, I came home. There was no point in protesting about events in foreign countries while ignoring the situation in your own."

The first demonstration she took part in was a protest in Belfast's Shaftesbury Square: "I looked over to RUC lines and saw my cousin who was a policeman. Our eyes met but we both made the decision not to acknowledge each other. He didn't want to know me and I didn't want to know him.

"On the Burntollet march [in 1969], there were loyalist counter-demonstrators with nail-studded cudgels. I saw the police and thought they would act but they started chatting amicably to the counter-demonstrators. I was witnessing what later came to be called collusion.

"I remember when we reached Derry being hit with something and running into the doorway of a unionist-owned department store, screaming as the blood ran down my face, and the shop assistants laughing at my terror. They'd dehumanised me."

McCormack, who later became president of the Irish Congress of Trade Unions, recalls individual acts of defiance: "I can still see my father-in-law putting on his good suit to go on a march. It was his way of dealing with the humiliation he met in his daily life, of asserting his dignity and that of his family.

"I remain in awe of women like Sadie Campbell who marched into the mayor's parlour in Derry to demand better housing and was arrested. There was such courage from people who owned nothing, who had nothing in the world but themselves. Women who endured rather than enjoyed life, who washed the dishes, and went out to protest on the streets, and went home and washed more dishes."

Cathy Harkin, who left school at 14 and worked in a shirt factory, was in the thick of the civil rights movement. Her son Terry, who was six years old on 5 October, 1968, recalls her coming home from the march badly bruised: "We lived with my granny. My mother sold the United Irishman newspaper. Before 5 October, I remember my mother having to sit on the street waiting for it to arrive because granny wouldn't let it into the house.

"After 5 October, my granny changed. All sorts of rebels and radicals were allowed to come and go from our house around the clock. Civil rights posters were made in our livingroom. The house was always full of the smell of ink and paint.

"Even though I was no age, I'd be carted to civil rights meetings in Dungannon, Strabane, and Belfast because there was no such thing as crèches or childminders. I remember making my first confession and then watching police drenching demonstrators with the water cannon."

Bloodstains

Harkin was 10 when British paratroopers shot dead 13 unarmed civilians in Derry. "A few days later, my mother and I visited the home of civil rights activist Brigid Bond. I went to the bathroom and sitting there was one of the banners carried on Bloody Sunday. It was covered in bloodstains, and in the corner was a white goo which I later found out was part of the eye of one of those killed.

"I'd been an avid reader of British Commando comics. I went home, gathered them and my toy Action Men, put them into a biscuit tin and burned them all."

Several months later, Harkin was hit with a rubber bullet while stoning the British army. While his mother went on to become one of the founder members of Women's Aid and a staunch critic of the armed struggle, Harkin joined the INLA. Cathy Harkin died of cancer aged 45.

Her son is immensely proud of his mother and stresses that the civil rights movement wasn't universally popular: "There were Uncle Toms in America and there were Castle Catholics here. There were plenty of fence-sitters and plenty who said the civil rights activists had brought all the trouble on themselves. But there were also more idealists than there are today. People have become less politicised and more complacent."

Willie Breslin and Dermy McClenaghan acknowledge the North has changed significantly but insist there's still more work to be done. "The PSNI (Police Service of Northern Ireland) is an improvement on the RUC, there are more decent people in the force," says Breslin. "But there remains an old Special Branch element which exerts a hold at a senior level, and crime in nationalist areas isn't tackled adequately because some of the criminals are informers."

Breslin regrets there is no cross-community, left-wing party. McClenaghan says "DUP antics" at Stormont show sectarianism still prevails. He believes the Belfast Agreement institutionalised sectarianism. He regrets that most jobs created in Derry are "low-paid, mind-numbing ones in call centres or the service industries."

The establishment of the North's Housing Executive ended most housing discrimination but there are still injustices. In north Belfast, 83% of those on the housing lists are nationalists.

Inez McCormack recently visited Catholic women living in the Seven Towers flats. "It felt like I was back in the Derry slums," she says. "There was damp on the walls, pigeon waste on the landings, and sewage coming through the sinks."

She is concerned about those remaining outside "the golden bubble of the new good times." Nineteen of Northern Ireland's top 20 most deprived areas are in north and west Belfast or Derry. Catholics make up 72% of those in the North's 500 most deprived areas, and only 20% of those in the 500 most affluent.

McCormack's civil rights days taught her much. "I learned when injustice exists, never accept the authorities saying 'Now isn't the right time for change' or 'We need to move slowly.'

"I discovered people can settle for reform when their own comfort is secured but you should never be satisfied until the most excluded in society get justice. I learned that injustice can provoke anger, and there's nothing wrong with anger if used constructively. There is a great deal to be said for not knowing your place."