Leon Greenman was the only Englishman to be sent to Auschwitz. His wife and son died in the gas chambers, and for two and a half years he was a slave labourer, subjected to beating and experimentation. He vowed that his life thereafter would be devoted to keeping the memory of such horror alive. His final decades were spent in unceasing testimony against the crimes of Nazism, and determined campaigning against any modern revival of fascism.

Greenman was born one of six children in Whitechapel, East London, in 1910. His mother died when he was 2, and three years later he was taken to live with his father’s Dutch parents in Rotterdam. He trained as a barber and was a keen boxer in his youth; both skills were to help him to survive the camps.

In 1935 he married Esther (“Else”) van Dam and settled near her family in Rotterdam. Greenman worked as a bookseller, travelling regularly between the Netherlands and London. As the political situation worsened in the late 1930s, he considered moving back to England, but was reassured by Neville Chamberlain’s promise of “peace in our time” and decided to stay. His son, Barnett, was born in March 1940. Greenman was told that, as a British passport holder, he would be evacuated in the event of war. But when the Nazis invaded in May 1940, diplomatic staff fled and he was left stranded.

Even under occupation Greenman assumed that he would be safe. He gave his savings and passport to a non-Jewish friend for safekeeping. But the friend panicked and burnt the documents. Restrictions on Jews grew tighter, and then the Nazis began to round them up for deportation.

They came for Greenman on October 8, 1942. “I remember the light of a torch shone in my eyes and I heard a man’s voice shout out, ‘Greenman!’ ” he later recalled. “Up stormed two policemen. I can still see them, in black leather jackets and wellingtons.”

The Greenmans were taken to the Westerbork camp in eastern Netherlands, where Greenman insisted that there had been a mistake; he was British and should be released. Documents proving this arrived shortly after Greenman, his wife and son had been put on a train to Birkenau in January 1943.

In carriages with blacked-out windows they travelled for 36 hours with no food or drink, not knowing where they were going. Greenman later said that the first clue came when they arrived at the camp, finding the deep snow studded with abandoned suitcases. The owners had already been killed.

“Esther and Barney were marched about 20 yards away to a queue of women,” Greenman later wrote. “I could see her clearly against the blue lights. She could see me, too, for she threw me a kiss and held our child up for me to see . . . We had been promised that we could meet at the weekends after our work was done.”

He never saw either of them again. After the war he discovered that they had been gassed a few hours later. But at the time he refused to believe that they were dead. “It was my belief that they were still alive that kept me going.”

His arm was tattooed with his camp number, 98288. Early in his time in the camp Greenman prayed for help from God. “If He would protect me from being beaten up, from dying of hunger and just get me out, I would tell the outside world what happened in the camps.”

After six weeks those who could work were separated from those who would be killed. “We were forced to undress and to walk past two desks. At every desk sat an SS officer. If you were declared fit, they directed you to the right. If you weren’t, you went left. I walked past those tables. They pointed to the right.”

As well hauling bricks and cement, Greenman worked as a barber, and he believed that it was this skill, along with his fitness, that allowed him to survive. In the evenings he would also sing to entertain the “kapos”, the prisoners who led the work gangs. In September 1943 he was transferred to the Monowitz industrial complex within Auschwitz, where he remained for a year and a half. In his autobiography, An Englishman in Auschwitz (2001), Greenman described the grinding horror of life in the camp — the constant hunger, the search for water in snow and wet grass, the sickness and lice, the regular cullings of the weak, the sight of desperate prisoners scrabbling in the dust for scraps of potato peeling. Greenman was subjected to medical experimentation on his genitals and many beatings. He remembered the SS officers as particularly cruel, but they were not the only ones. “The kapos were the bullies who dealt out beatings to us. Ex-professional murders, rapists, criminals. . . these were the ones who made our lives a misery.” Of the 700 passengers on the train from Westerbork, only Greenman and one other man survived.

In early 1945, with the Red Army approaching, the camp was evacuated. In the bitter winter Greenman was forced to join a 90-kilometre “death march” away from the Allies, first to Gleiwitz, then on to Buchenwald. “The camp uniforms were thin and my feet had gangrene. When we reached Buchenwald I felt I was near the end. I could hardly lift my legs.” But on April 11, Greenman discovered the guards had fled. The camp was liberated by the American army later that day.

Remarkably, Greenman needed little hospital treatment. After the war he returned to England, where he worked on a market stall to support his brother’s family. He also performed occasionally as a singer. He gave his first interview, to the Evening Standard, on the way out of Buchenwald, but it was not until the 1960s that he devoted himself more fully to the pledge he had made in Auschwitz.

In 1962 he was in Trafalgar Square, where Colin Jordan, the leader of the National Front, held a rally. Horrified that such sentiments could still be expressed, he devoted the rest of his life to telling his story as widely as possible.

Well into his nineties he visited schools around the country, holding pupils rapt with his experiences, and letting them examine the tattoo on his forearm. Thousands of children heard him, and many wrote to tell him how he had transformed their attitudes.

In 1995 the Jewish Museum in North London established a permanent gallery on Greenman, to which he gave his photographs and mementoes, including his wife’s wedding dress. Greenman never remarried. He would come to the museum to talk to visitors himself every Sunday, and more often when school parties came. An accompanying book, Leon Greenman Auschwitz Survivor 98288, was published in 1996. He returned regularly to Auschwitz, guiding groups round the camp and recounting his experiences. He was appointed OBE in 1998.

Greenman became a vociferous campaigner against the far Right in any form. In the 1990s he took a leading role in a 60,000-person march demanding the closure of BNP headquarters in southeast London, and was involved in many protests against giving the party platforms to spread its views.

For his stand, Greenman had bricks thrown through the window of his house in Ilford, East London, and was forced to install mesh shutters. He received regular death threats and Christmas cards expressing disappointment that the Nazis had not finished the job. Having seen one seemingly civilised society collapse into murderous barbarism, Greenman could not believe Nazism was part of the past. “My purpose now — my duty — is to tell people what happened,” he said in 1998. “Whatever some historians say, it happened. And it could happen again.”

Leon Greenman, OBE, barber, market trader and death camp survivor, was born on December 18, 1910. He died on March 7, 2008, aged 97