The Thomanerchor of Leipzig in Germany, once led by Johann Sebastian Bach, will be the focus of much celebration this year

It has survived the Thirty Years War, the plague, and both the Nazi and Communist regimes. This month one of the world's oldest choirs – Johann Sebastian Bach was its choirmaster in the 18th century – marks its 800th anniversary with an array of celebrations.

The Thomanerchor is being feted across Germany, particularly in its native Leipzig: exhibitions, religious ceremonies and film documentaries will focus on the remarkable history and achievements of an institution that is arguably the country's greatest living cultural export. The choir, which has around 90 schoolboy members, is also being hailed for its founding egalitarian and educational principles, which endure to this day.

Bach joined the choir when it had been running 475 years; for 27 years, he was its cantor, or choirmaster, with the task of composing a new cantata for the boys every week, an act that indelibly bound the choir and composer and gave the Thomanerchor its abiding nickname, "the Bach choir". Its trademark sound, bright and clear, is said to stem from its years under Bach's strict but creative leadership.

The relationship with the composer remains an emotional one. When they sing in the St Thomas church, metres from the grave in which Bach is buried, the choristers describe feeling close to the composer, even more than 250 years after his death. "If the choir is singing well together you can certainly feel the presence of Bach," said Konrad Didt, 19, who is in his final year with the choir.

The familial atmosphere is said to have much to do with a system that is as old as the choir itself. Nine or ten Thomaner – all of different ages, from nine to 19 – live together in Stuben, or parlours, which change personnel every year. As a result, older boys look after the younger ones: helping them with their homework, feelings of homesickness or learning a Bach cantata.

"This means that not only do the boys look after each other, but it's possible to let 65 boys out on their own in Tokyo and you can be sure that all of them will turn up punctually to rehearsals," said Christian Wolff, the pastor of St Thomas Church. In recent years, in line with other subtle modernisations, the Stuben system has been adjusted to allow the boys more private space.

Many of this year's celebrations, including a film documentary, will focus on the choir's astonishing longevity – how it has managed to survive not just the Thirty Years War and the plague – which almost destroyed it – but also the second world war, when it was moved to a safe destination outside Leipzig after the school was destroyed in a bombing raid. The boys were driven into the bombed-out city in a lorry to sing their Sunday concerts every week. "People used to flood the church, because the choir gave them great solace at that time," said Stefan Altner, the choir's general manager.

The choristers were forced to join the Hitler Youth movement during the Nazi era, but managed to remain relatively isolated from the prevailing politics.

After 1945 the choir found itself locked in communist East Germany. While most of the boys were forcibly recruited to the communist youth movement, attempts by the atheist regime to change the religious repertoire were dropped when it was realised the Thomanerchor was the country's most esteemed cultural export and should be preserved.

"You could say that Bach is our patron saint in this regard," said Altner.

The choir's leadership also resisted attempts to switch the foreign language that the boys learned from Latin to Russian, arguing that Latin was vital for the choir's ability to perform church music.

Experts say its place as something of an island in both Nazi and Communist times helped it preserve its agile and virtuoso sound, which has ensured its international standing.

However, surviving dictatorships is one thing. Now the choir faces its biggest challenge ever as it struggles to recruit new members. Fewer young Germans are exposed to classical music in the age of the mp3 player. The choir has been sending talent scouts into kindergartens to expose young Germans to the music of Bach in the hope of being able to spot potential choristers.

It also has plans to open its own kindergarten as a way of preserving its future.

Singing for their supper

St Thomas, part of a monastery, was founded in the 13th century as a school for the poor, which accepted musically gifted students from all over Germany. Those who passed an entrance exam were given free tuition, room and board in return for singing.

It came into its own in the 16th century when Germany became a country of choirs after the Reformation as communal singing started to define public and private life with every workplace and village boasting its own choir.

The Thomanerchor took centre stage and maintains to this day a position as one of the leading choirs in the world. A long-standing tradition encourages its all-male lineup to tutor each other in everything from table manners to how to master a Bach cantata.