He was captured by the Germans while attacking Erwin Rommel's forces near Tobruk, Libya, and saw his best friend killed next to him.

[5] After his prisoner transport ship was torpedoed he claimed to have escaped to Greece by floating ashore on top of a packing crate, but was recaptured after landing.

With that simple exchange between the two of us I had given away the protection of the Geneva Convention: I'd given my uniform, my lifeline, my best chance of surviving that dreadful place, to another man ...

While British POWs were forced to work six days a week, they could use their free time to play football and basketball.

[8] Avey agreed, and describes the plight of the Jews: I am telling you I know without exaggeration, nearly 200,000 prisoners in Auschwitz were worked to death.

[9]Avey explained to The Daily Telegraph that he was the type that needed to see things for himself: My mates didn't want me to do it but they agreed because they realised I was going to do it, and that was that.

Although suffering from tuberculosis he caught in the camp, he broke away undetected, then made his way through Silesia, Czechoslovakia and Germany.

[5][13][10] During the march Avey saw an estimated 15,000 dead prisoners, recalling that "the road was littered with corpses.

[15]The author Sir Martin Gilbert explains that by 1947, after the Nuremberg Trials were finished, "people just wanted to get on with their lives".

Besides tuberculosis, Avey suffered from posttraumatic stress disorder (PTSD) before it was recognised as a medical illness, a condition few people were aware of.

[15] When war crime prosecutors later sought Avey's testimony for the Nuremberg Trials, they were unable to locate him.

"[14] Avey explains "The sad irony was that I went in there to find out the truth, so I could tell everybody about the horrors of the Nazi regime.

As a result, the BBC began production of a documentary, discovering the name of the young Jewish prisoner Avey had befriended in Auschwitz, Ernst Lobethal.

"[14] When asked why he risked his life to infiltrate the Jewish sections of the concentration camp, he states that he needed to see for himself "the unspeakable things being done to the Jews at Auschwitz."".

Years later, Susanne learned that her brother had survived, in part thanks to Avey, and had lived in America with his new family until his death.

"[10] Ernst, like Avey, refused to burden anyone with his own suffering and never talked about Auschwitz until very late in life.

"[17] Avey married twice and pursued a career in engineering, which culminated in him building a factory near Newcastle.

After retirement he became active amongst ex-POWs seeking compensation for wartime imprisonment[18] and began to talk about these experiences.

In 2005 the Daily Mirror reported that Avey claimed to have swapped uniforms with Ernst and entered Birkenau where he witnessed prisoners being sent to the gas chambers.

That autumn Rob Broomby, a reporter from the BBC, who had known of Avey's story for some years, was able to trace Ernst's sister in Birmingham.

He learned that Ernst had survived the death march and emigrated to the United States where he lived to the age of 77.

[10] Broomby also discovered that before his death, Ernst had recorded a video testimony of his experiences in Auschwitz, in which he mentions the British soldier whom he knew as "Ginger" who obtained cigarettes.

An article by Broomby published at the time of the first broadcast suggested that he and the BBC had accepted the "break-in" story as also confirmed.

Brian Bishop, a British POW interviewed by Walters, while he did not claim to know Avey, stated "I can't understand how he did it.

"[23] Similar doubt about the feat was expressed by Ron Jones, another British POW, who also found it hard to believe that Avey, a tall, fit, strong Englishman, could have passed himself off alongside "starving six-stone Jews.