When John Hajdu was three, his parents gave him a teddy bear small enough to fit into his hands. Eighty-six years later, that bear is the only surviving object from his childhood - and it's about to become a museum exhibit, because apparently nothing says 'childhood interrupted' like a stuffed animal that outlasted the Nazis.

From 31 July, 'teddy' (creative name, John) will go on public display for the first time at the Imperial War Museum's new exhibition, Childhood in War. The bear will sit in a recreated Second World War bedroom, surrounded by toys, books, and personal possessions that ask visitors to ponder what happens when play, education, and family life get rudely interrupted by global conflict.

Hajdu's story involves his father being sent to a labour camp, his mother to a concentration camp, and himself hiding in a neighbour's cupboard before ending up in the Budapest ghetto. 'There was absolutely no chance of being a kid,' he says, which is putting it mildly. He was isolated, forbidden from parks, cinemas, swimming pools, or cafes - basically any place where a child might have fun.

The exhibition doesn't stop at the Second World War. It includes a full-size railway carriage, a wartime classroom, a Cold War living room, and testimonies from kids currently living through conflicts in Ukraine, Sudan, and Afghanistan. Because apparently we haven't learned enough from history to stop making new exhibits.

There are comics warning about landmines, a red knitted jumper from the Kindertransport, and a poem by a 15-year-old Afghan girl who watched the Taliban return to power: 'I witnessed how that day darkened not only Kabul’s sky, but also the dreams and hopes of so many.' Heavy stuff.

Hajdu's mother survived Mauthausen concentration camp but returned with broken ribs, smashed teeth, and lasting psychological scars. After the Hungarian uprising, Hajdu and his mother walked 40km and crossed an icy river to reach Austria, eventually arriving in Britain in 1957 with teddy in tow.

Now a grandfather of four, Hajdu spends his time speaking in schools about surviving the Holocaust. 'My small story is an example that you can survive,' he says. 'It’s absolutely vital that the younger generation takes on what we’re doing.'

As for teddy, leaving his home for the first time has been surprisingly difficult. 'I find it difficult to look at the desk where he normally sits,' Hajdu admits. But the bear is now ready for its close-up, proving that even the smallest objects can carry the weight of history - and that a teddy bear's retirement plan can be surprisingly eventful.