"I remember working in a goods yard overlooking the railway platform. I saw with my own eyes an SS man approach a woman who was holding a crying child and telling her to make it stop. When she couldn't he smashed the child's face with his fist, no doubt killing it…
"I weep for that child every day," he says. His gaze is penetrating, not least because of a glass eye, the result of a blow from an SS officer's pistol after Avey cursed him for beating a Jew.
Avey, a former Desert Rat, was taken prisoner in 1942. The following summer he was deported to Auschwitz, and interned in a small PoW camp on the periphery of the IG Farben factory, where he worked alongside Jewish inmates from the main death camp.
"I remember Hungarian Jews arriving in 1944 - big, strong men. Within four months they had been reduced to skeletons, to the living dead. I knew that at the end of the war someone would have to answer for this and I wanted to be there, to give evidence. I've never been one for doing nothing."
And so a plan evolved, which would involve swapping places with a Dutch Jewish slave labourer, Hans, whom he passed at the beginning and end of their shifts at the factory.
Ernst Lobethall, a German Jew from Breslau, who worked alongside him at the Farben factory made the plan a reality. "I discovered that Ernst had a sister, Susana, living in England and so wrote to my mother cryptically asking her to tell Susana that Ernst was alive. She posted 200 cigarettes to me via the Red Cross and incredibly these arrived four months later. Cigarettes were the ultimate bartering tool and Ernst used some as bribes to help get me into Auschwitz."
But even with such meticulous planning, what if Hans refused to swap back after his day away from hell?
"It was a chance I was prepared to take. I knew the inmates of Auschwitz were bring treated worse than animals.If I could only see, I could bear witness."
And so, after swapping in a disused shed, Avey, with his head newly shaven and an affected stoop, passed beneath the Arbeit Macht Frei [work makes you free] sign. He was herded into the camp, carrying the bodies of those who had died that day. He passed a body hanging motionless from a gibbet, a warning to others who tried to escape. After a two hour roll-call the inmates were given rotten cabbage soup and sent to their baracks. No one noticed Avey as he slipped in among the lice-infested bunks. "The air smelt of death," he says. "In sleep, many relived their terror - a beating, a hanging or the loss of a child on arrival. For these people there was no escape."
Lobethall had bribed Avey's bunkmates with cigarettes so that they would talk to him without giving him away. They provided details of what went on in the gas chambers and the hospital block, where the ill lay before being gassed.
The following morning, Avey joined a group to march out of the camp and go back to work. He held his breath. Would the Dutch Jew be waiting for him to switch back? But Hans kept his bargain.
Incredibly, Avey did another swap with Hans several months later: "I felt I wanted to see more, and I did, though it was more of the same. More death, more despair."
In 1945, as the Soviet Army closed in, the Nazis abandoned the camp and herded thousands of prisoners on a death march. Avey, by then suffering from tuberculosis, was among them. True to form, he grabbed the opportunity to escape and somehow found his way to Allied lines. He arrived at his parent's Essex farm two days before VE Day: shrunken, ill, half-dead.
In I947, he went to the military authorities to give his account of Auschwitz. He could feel their disbelief. The disillusion was crushing and for the next 60 years he kept his experiences bottled up inside. Indeed, he only told his wife Audrey of what he had experienced about six years ago.
It was only during an interview with BBC reporter Rob Broomby on the subject of war pensions that he found his voice. He later co-wrote his book with Broomby.
Avey remains a man with a mission. As survivors pass away and Holocaust deniers try to peddle their fiction, he has an unstoppable urge to talk about his experiences and he will be guest of honour at the 60th anniversary dinner of the Manchester-based Jewish day care home for the elderly, the Nicky Alliance, on September 15.
"Auschwitz was an evil place. Even nature gave up. I never saw a bird in the sky or a leaf on a tree. I was foolish, inquisitive, I took a chance with my life. But I survived and I need to tell the world what I saw so that it can never happen again."
