Dr George Daniels was the first person in history to make every component of a watch, from scratch and by hand.
It was a task which involved mastering more than 30 long-forgotten skills to painstakingly craft 150 individual components, before developing a mechanism which ensured absolute accuracy.
Each of his creations - regarded as works of art by many - could take more than 2,500 hours to complete.
And it was all done from a single workshop at the back of his home in the Isle of Man.
Now some of the master watchmaker's greatest works are to be auctioned as part of a collection of historically important timepieces he amassed during his life in one of the most eagerly anticipated horological events in recent years.
Watchmaker Roger Smith, who moved to the Isle of Man in 1988 to work with Dr Daniels, said: "It is the equivalent of one man designing and making every single component of the greatest car the world has ever seen in his garage at home, right down to putting hide leather on the seats and hand stitching it.
"They are without question the greatest watches the world has ever seen."
When north London-born Dr Daniels made his first pocket watch in the 1960s many of the skills needed were no longer practised.
Mr Smith, originally from Greater Manchester, said: "The watchmaking industry in England had disappeared.
"Some of the skills could take years to master. Traditionally one man would sit down every day and he would make wheels, another skilled craftsmen would make pinions.
"There are five trades alone involved in making one pocket watch case and you would have hand makers, dial makers and so on. He did the lot."
In a remarkable career spanning 60 years, Dr Daniels dedicated himself to the pursuit of watchmaking perfection.
When he died at the age of 85 in 2011 he had completed 24 of the most extraordinary and technically advanced watches ever made.
"He was like a god to some people," explained Jonathan Hills, director of Sotheby's clock department and a lifetime friend of Dr Daniels.
On 6 November Dr Daniels' private collection of watches and clocks, including several of his own creations, will go under the hammer at Sotheby's in London, for whom he spent four decades acting as a horological consultant.
Mr Hills said: "A collection as significant as this is a once-in-a-lifetime occurrence. In horological circles he is revered all over the world."
The 134-lot collection is expected to raise more than £5m for the George Daniels Educational Trust, which helps students seeking higher education in the fields of horology, engineering, medicine, building or construction.
It ranges from a simple cuckoo clock with an estimated value of a few hundred pounds to a clock made by the English watchmaking pioneer Joseph Knibb in 1677, which carries an estimated price of close to £1m.
It will also include the Daniels' Space Watch, designed to commemorate the first moon landing, and many of his groundbreaking watches.
Mr Smith, who considers Dr Daniels to be the "greatest horologist of all time", said: "George devoted his life to the improvement of the mechanical timekeeper.
"Each piece was added to the collection because of its unique qualities.
"George would have been delighted knowing that they will be going to new owners who will continue to enjoy them just as he did."
'People were speechless'
Mr Smith has recently returned from Hong Kong, where he said collectors were showing "unprecedented interest" in the collection.
He said: "It traces the life's pattern of a genius. It took a while to explain that just one man had made these watches from scratch, in a humble workshop in the Isle of Man.
"People were speechless.
"Every single watch he made had at least two major technical advancements and when completed each one was the most technically advanced watch in the world."
Speaking to the BBC in 2010, Dr Daniels said: "In my career I just wanted to make English watches the most superior, which they always were, and we've achieved that condition again here on the Isle of Man."
The most successful of Dr Daniels' inventions, the co-axial escapement, won him international acclaim and is regarded by experts as one of the most significant horological developments in 250 years.
Mr Smith, 42, said: "The co-axial escapement was so good that it was taken on by the Swiss watchmaking industry and in particular Omega.
"The escapement gives a higher degree of accuracy over longer periods than lever escapements.
"George never accepted what had been done before. He always studied and examined his work and improved upon it."
Jonathan Betts, senior curator of horology at the Old Royal Observatory, said: "The body of work which George [Daniels] produced is monumentally important.
Passion for racing
"He has done more than any other individual to ensure that mechanical watchmaking is not just a part of history but instead has an incredibly bright future.
"His work from the 1970s onwards contributed a huge amount to the renaissance of mechanical horology. Things looked bleak for the mechanical watchmaking industry with the introduction of quartz technology in the 1970s but Dr Daniels had other ideas and now it is flourishing."
The auction itself was planned with Sotheby's many years before Dr Daniels' death in October last year and is a natural conclusion to that long relationship he had with the company.
Over the years representatives from Sotheby's made several visits to Dr Daniels' home in the Isle of Man to both catalogue and research his work to gain a full understanding of it.
Dr Daniels, who was born in Edgware in 1926, won numerous awards during his career, including the Gold Medal of the British Horological Institute.
When he was not making watches Dr Daniels loved to race cars.
In July, a vintage car he owned sold for more than £5m at auction. The "Birkin" Bentley, which went under the hammer at the Goodwood Festival of Speed, became the most expensive British car ever sold at a public auction.
The entire collection, including a 1954 Bentley R-Type, a Bentley Tourer and a 1907 Daimler, was sold by Bonhams for about £10m.