It was finding a suitcase bearing her family name which hit Emma Geiringer hardest.

A pile of hundreds of suitcases lies behind glass at Auschwitz I; other mounds are of shoes, spectacles, and human hair.

Emma, 17, from Holy Cross School in New Malden, knew through a family friend the case was there.

She said: “I cried quite a lot at that. I knew the story but you don’t really think it’s real.

“I don’t know who that person was or what happened to them.”

Auschwitz II-Birkenau, three kilometres down the road, is a deeply sinister place purpose-built for mass extinction.

Its low huts and miles of once-electrified barbed wire stretched into the murky distance, left as they were almost 70 years ago.

Laura Winstone, 16, from Tolworth Girls’ School, said what moved her most was looking out of the watchtower guarding the entrance, and described the vast camp as “eerie”.

She said: “It was like a battery farm, just looking around and seeing how bleak it was, and miserable.”

More than 200 school students from across south London visited the camps on Thursday through the Holocaust Educational Trust.