Mike Lynch, who died in the wreck of his yacht at the age of 59, was sometimes described as “the British Bill Gates”. It was a gross exaggeration, but Lynch could claim two parallels with Gates: he developed leading-edge technology (in his case in machine learning, or AI) and, unlike so many British scientists, he learned how to turn it into commercial success.

Such was his success that his company, Autonomy, was valued at $11 billion when he sold it to Hewlett-Packard in 2011. The fallout from the sale, however, would overshadow his technological achievements and sparked a national debate over the circumstances under which British citizens could be extradited to the US.

Lynch founded Autonomy with two partners in 1996. The software allowed a computer to sift through vast amounts of disparate information, including phone calls, emails and videos, and to recognise words. He told the Independent in 1999: “Our technology works by looking at words and understanding the relationships, because it has seen a lot of content. If it sees the word ‘star’ in the context of a film, it knows it has nothing to do with the word moon. Because it works from text, it can deal with slang and different languages.”

Autonomy became a leading company in Cambridge’s Silicon Valley cluster and set up a base in San Francisco. “We knew we had to be successful in America. It was a case of, ‘Go west, young man, go to San Francisco and be ignored.’ They found it hard to believe that someone from England could have anything powerful.” Lynch found what he called the “cold-hearted schmooze” of securing financing difficult.

But Autonomy’s software, which allows computers to identify and match themes and ideas, and sort through vast amounts of data, has been licensed to more than 500 clients, including the US State Department and the BBC. It floated on the Nasdaq in 1998 and on the FTSE 100 in November 2000, though its £5.1bn value would be halved within months amid the collapse of the tech boom and accusations of over-promotion. In 2005, it bought a major US rival, Verity, for $500m.

Lynch’s profile rose accordingly. In 2006 he was appointed OBE for services to business and the following year he joined the BBC’s board of governors. In 2011 he became a member of the government’s Council for Science and Technology and was named the most influential person in British IT by Computer Weekly. In 2014 he was elected a fellow of the Royal Society.

Though softly spoken, he had a reputation for toughness, tinged by a fondness for James Bond that led to Autonomy naming its meeting rooms after Bond villains and having a tank of piranhas in reception (Lynch claimed the tank belonged to one of his business partners.) Asked about a corporate culture in which people were “a bit fanatical,” he replied, “This is not the place for you if you want to work a 9-to-5 job and don’t like your job.”

Lynch was born in Ilford, east London, to Michael, a firefighter, and Dolores, a nurse, and grew up in Chelmsford. He won a scholarship to the independent Bancroft’s School in Woodford Green, after which he gained a degree in natural sciences at Cambridge, where his PhD in artificial neural networks, a form of machine learning, has been widely studied ever since.

A saxophonist and jazz enthusiast, he set up his first company, Lynett Systems, while still a student, to produce electronic equipment for the music industry. He would later attribute some of his hearing loss to modifying synthesizers for bands. He cited his own experience to highlight the difficulties of finding finance for start-ups in Britain. He eventually negotiated a £2,000 loan from one of Genesis’ managers in a Soho bar.

Lynch’s next venture grew out of his research. In 1991, he founded Cambridge Neurodynamics, specializing in computer-based fingerprint recognition. He then founded Autonomy.

The pinnacle of his success seemed to come in October 2011 when Autonomy was bought by Hewlett-Packard for $11 billion, earning Lynch an estimated $800 million. Shortly afterwards, he set up a new company, Invoke Capital, to invest in technology companies, and he and his wife, Angela Bacares, whom he had married in 2001, invested around £200 million in Darktrace, a cybersecurity company.

But just 13 months after selling Autonomy, HP announced an $8.8 billion write-down on the assets “due to serious accounting irregularities, disclosure errors and outright misrepresentations” that it claimed had artificially inflated the company’s value. Authorities investigated, and despite Britain’s Serious Fraud Office finding insufficient evidence, U.S. authorities charged Lynch with fraud in 2018. Shortly after, Autonomy’s chief financial officer, Sushovan Hussain, was found guilty of fraud and sentenced to five years in prison.

In March 2019, HP followed up with a civil lawsuit for fraud in London. Lynch spent days on the stand as the civil trial dragged on for nine months. It ended in January 2022 with the judge ruling that HP had been substantially vindicated, but that the damages would be far less than the $5 billion they had sought.

Meanwhile, U.S. authorities sought Lynch’s extradition on criminal charges of conspiracy and fraud. Despite statements from senior politicians and allegations that U.S. authorities were attempting to exercise “extraterritorial jurisdiction,” a district judge ruled in favor of the extradition.

A request for judicial supervision and a new appeal were denied and in May 2023 Lynch was flown to the US to be placed under house arrest in San Francisco, facing the prospect of a 25-year prison sentence.

Lynch was charged with wire fraud, securities fraud and conspiracy and pleaded not guilty on March 18 of this year, along with his former treasury vice president, Stephen Chamberlain. They were acquitted of all charges on June 6. Chamberlain died after being struck by a car on August 17.

Lynch declared that he wanted to get back to what he loved most: innovating. But he had little opportunity to do so. He soon went on a trip to celebrate his acquittal, with family, colleagues and business associates. It ended with the sinking of his yacht, Bayesian – named after the 18th-century mathematician Thomas Bayes, whose work on probability influenced much of his thinking – in a violent storm off the coast of Sicily.

Lynch is survived by his wife and eldest daughter, Esme. Their other daughter, Hannah, was also aboard the Bayesian.