Denis Avey - who is now 91 - spent the latter stages of the Second World War as a prisoner of war in a camp adjoining Auschwitz. He swapped places with one inmate and spent two nights amid the full horror of "hell on earth".
Mr Avey always thought that inmate, Ernst Lobethall, had died - but in fact he had survived until 2001. Here, he meets Mr Lobethall's sister Susana Timms for the first time - and together they watch video testimony recorded by Mr Lobethall before he died.
Footage courtesy The Shoah Foundation