When the Festival of Britain opened in London in 1951, exuberantly marking the end of post-war austerity, Cathal Gannon, a carpenter who worked in the Guinness brewery in Dublin, visited the city to see relations and soak up the culture. A keen musician and a fan of old instruments, he came across a harpsichord, made in 1777, while at an exhibition in Chelsea.

Then he had an idea that would have extraordinary repercussions. He decided to build a copy of the instrument made famous by composers such as Bach and Mozart and started making meticulous diagrams of its internal structure. It was a task that would take him more than two years.

Gannon had built and repaired instruments before, sometimes working from crude drawings in woodwork magazines. Originally a hobby, it became an obsession and a challenge that would take over his life. Charles Gannon, his son, describes the incident in his new biography of the instrument maker, proving it was typical of the man.

Although his father was not a difficult man, there were areas where he would never compromise. He was an autodidact of the old school. He grew up in a Dublin working-class family whose members had been carpenters and brewery craftsmen for generations. He acquired his knowledge slowly, piece by piece, driven by a curiosity and eventually a love of antique craftsmanship.

He was a fine example of an all-but-extinct breed: the self-taught, working-class expert. He emerged from a society where music — sung and played live — was always there in the background. His mother had paid £48 — a staggering six weeks of her husband’s wages — for a piano in the 1920s.

James Joyce, in Dubliners and Ulysses, depicts many similar scenes, where music was made and discussed in Dublin homes. The motivation was not upward mobility, at least not in the sense we use it today. There was precious little social mobility in that class-ridden society, where family origins and breeding were believed to categorise you for life.

What made Gannon different was that, over many years, his hobbies and interests gradually combined and brought together the fine skills he had acquired through his work. That harpsichord, completed in 1953, was the first built in Ireland for more than 150 years.

As expert musicians — including John Beckett, cousin of Samuel and a dedicated harpsichordist — soon discovered, Gannon had achieved something remarkable. He was no amateur building mock antiques as a hobby. His harpsichords played a crucial role in the rediscovery and appreciation of early music — including the works of such composers as Bach and Mozart as they must have sounded to their makers.

The arrival of the piano at the start of the 19th century marked a turning point in musical history. Beethoven is perhaps the last composer to have written harpsichord music. His successors, such as John Field, quickly adopted the newer, more flexible instrument.

The arrival of recording techniques a century later sparked a minor harpsichord revival. The original instruments were now unplayable antiques, but musicians were keen to re-create the original sound of a Bach fugue. New harpsichords were built, but their makers could not resist the temptation to tinker with them, incorporating modern materials and construction techniques in an attempt to improve on the originals.

The results were not satisfactory, at least not to the finely tuned ear of experts such as Beckett. They knew modern methods and materials created the wrong sound. Then along came Gannon. His philosophy was simple. The master instrument makers of the 18th century knew what they were doing and their techniques had been refined for generations. Since you could not improve on them, the best you could hope for was an exact copy; something he did with patience and attention to detail.

One can see various strands combining in Gannon’s creative career. Partly by temperament and perhaps because of his training, he seems not to have wanted to be original. Unlike playwrights such as Sean O’Casey, he did not consider himself an artist. But his musical family background, the fine skills of a master craftsman and his acquired passion for 18th-century refinement merged in his work to create for him an enviable reputation.

In a sense he is a link to a more distant past. For many centuries an artist was primarily a craftsman, often anonymous. It was the Romantic movement of the early 1800s and the time of Beethoven and the piano that pushed artistic originality and genius to the forefront. It has taken us a long time to understand that there are other, less assertive, forms of genius.