Seventy years after the start of the Spanish Civil War, veteran Bob Doyle tells Shane Hegarty about the role the Irish played.

Bob Doyle has referred to himself as a rebel without a pause. Brought up in the Dublin slums, he joined the IRA as a teenager, engaged in running battles with the Blueshirts, ditched the church and took up communism, and then found his way to Spain to fight in the civil war. The 70 years since have not been dull either.

He was a merchant seaman during the second World War and then worked with Fleet Street print unions and the underground unions in Franco's Spain. He has battled to commemorate the men he fought with in the International Brigade and marched on behalf of dockers, steelworkers and sailors. He still goes on protests when he can, most recently with the anti-war movement. He is among a dwindling band of avowed communists. And for good measure, he once took to growing marijuana in the back garden of his London house, only stopping after he was raided. By burglars.

"It all got pinched. And I couldn't go to the police about it," he says.

Doyle now lives in London, but when we meet the 90-year-old, he is staying in the Dublin home of his friend, Harry Owens. It is 11am the morning after an official launch of his memoir, Brigadista: An Irishman's Fight Against Fascism, at which he signed copies for a long queue of readers. He has not yet emerged for breakfast.

"He had a lie-in," explains Owens. "It's his first in about 20 years."

Doyle's story starts, as so many Irish autobiographies do, with misfortune and neglect. His mother was confined to a mental institution as a "religious lunatic" (probably post-natal depression), meaning that he spent his early years in an orphanage before being dispatched to work on a farm at the age of 10. Finally reunited with his mother, and living in Dublin's inner city, his youthful aspirations were stymied.

"There was nothing," he says, as he finally tucks into his breakfast. "Only unemployment. I had a bicycle and I would go around begging off the ships coming in for the Eucharistic congress. It was a terrible time. I remember Capel Street, and the last 100 yards were the worst slums. That and Jervis Street. There used to be wars between the streets."

He became politically active in the 1930s, and a beating by Eoin O'Duffy's right-wing Blueshirts after one demonstration left him with permanent damage in one eye. He joined the IRA, but was, he writes, uninterested in the nationalism. "Living in the slums as I did, the struggle over the question of Border became of secondary importance."

But the memoir takes a particularly unusual turn when, in 1937, he becomes one of the small band of Irish - including his former flatmate, Kit Conway - to join the Republican fight in Spain. By then, a separate, much larger group, led by O'Duffy, had gone to fight on the side of Franco's forces.

For Doyle, the battle in Ireland and that in Spain were one and the same.

"I thought there was a danger that Ireland would go fascist and that was one of the motivating factors in making up my mind to go to Spain," he explains in his book. "I didn't know much about Spain, but I knew my thoughts were that every bullet I fired would be against the Dublin landlords and capitalists."

That motivation became far more personal when on February 12th that year, Doyle's birthday, Conway suffered fatal wounds in Spain. "I went to avenge Kit Conway," he says now. "I went to Spain to avenge his death."

He was determined to fight, working his way to France, stowing away on a boat and refusing to be dissuaded by his arrest and expulsion when he arrived in Valencia. He persevered and eventually succeeded in reaching the Republican force, where his IRA experience saw him employed to train foreigners coming into the battle. But this wasn't enough for him, and he disobeyed orders and joined a group heading for the front line. And there, he says, he saw the reality of the fight. In Ireland, the Catholic Church was preaching against the Republicans, who were accused of massacres of clergy. But Doyle, who had abandoned religion, recalls defending a church against Franco's forces.

"I had a machine gun, but I had to throw it away because it was broken," he says. "I stood with a rifle and fired, and the bloke next to me was killed. Bullets were hitting the church behind me. We were under fascist attack, but in Ireland people were told they were defending the church. I stood up and tried to get killed, on account that this was it, that I was going to get killed anyway. And the rifle got so bloody hot."

He escaped on that occasion, but was captured soon afterwards as the line collapsed. Questioned and given a terrible beating, he was fortunate not to be executed. Instead, after a spell in a concentration camp, he was released as part of a prisoner exchange in 1939.

Doyle was among about 320 Irish people who went out to fight Franco (a quarter of whom were killed) and he has spent a large part of his recent years ensuring that their sacrifice is remembered. Does he think they are finally appreciated?

"I think so, judging by the results we've had here," he says. "We've had no trouble getting people to come [to the book's launch]. And we've got more sympathy than the other side."

The other side, of course, refers to those Irish who went to defend the Nationalists. He has found himself on the right side of history, and earned Spanish citizenship for his efforts. But still he refuses to settle into the mainstream. Is he still a communist?

"Yes," he says firmly. "I still am, because I still say if all of Russia was to be anti-communist I'd be the only one left."

"You're a natural dissident," Harry Owens chips in. "You're a dissident bloody communist too. You had rows with anybody in the party who tried to order you around."

Doyle was always at odds with his comrades, too.

"I never had a desire to go to Russia," he says. He always suspected that it wasn't a workers' paradise. "I knew people who went there and came back with stories - that's what put me off allowing me to put my name forward to go there."

He didn't believe everything he was told. "I half-believed, but I had doubts." But he still believes communism can be viable. "Yes, because it represents a different form of society."

Now living in London with his son, he returns to Dublin a couple of times a year. In October, he will return to Spain for events marking the civil war's 70th anniversary. He has returned many times since, as his wife was Spanish and he also worked with the underground during the years of dictatorship.

Like most of Europe, the country has changed since those days. But when asked if he thinks the battle between socialism and fascism could happen again, Doyle cites South America as a current example. What about western Europe - does he think it could return to those dark days? He thinks about it for a moment, takes a spoonful of muesli, and looks up. "I don't know. I only think about dying now," he says.

He wears a cheeky smile as he says it. Rebel without a pause indeed.

Brigadista: An Irishman's Fight against Fascism is published by Currach Press, €14.70