Mike Lynch, the software millionaire missing after the sinking of a superyacht off the coast of Sicily, is one of the few examples of a UK entrepreneur who has created a global technology company.

That fact has led to seemingly obligatory descriptions of him as “Britain’s Bill Gates” but, in truth, his story differs hugely from that of the Microsoft founder.

Less than three months ago, the 59-year-old was cleared of 15 counts of fraud he had faced in the US over the $11.1bn purchase of his company, Autonomy, by the Silicon Valley giant Hewlett-Packard in 2011, a case he feared would end with him dying in prison because of a lung condition.

“I have various medical things that would have made it very difficult to survive”, Lynch told the Sunday Times last month. “If this had gone the wrong way, it would have been the end of life as I have known it in any sense.”

Born in Ireland, Lynch was raised near Chelmsford in Essex, where his mother was a nurse and his father a firefighter.

He studied physics, mathematics and biochemistry at Cambridge University, eventually specialising in adaptive pattern recognition. His doctoral thesis is reportedly one of the most widely read pieces of research in the university library.

After launching a few early technology startups – including one that specialised in automatic number-plate, fingerprint and facial recognition software for the police – he created Autonomy in 1996.

Its software was used by companies to analyse huge caches of data and partly owed its efficacy to Bayesian inference, a statistical theory devised by the 18th-century statistician, philosopher and Presbyterian minister Thomas Bayes.

The superyacht that sank off Sicily during a violent storm in the early hours of Monday was called Bayesian.

Autonomy was an almost immediate business success. The company floated in Brussels in 1998, and rapid growth coupled with the dotcom boom would lead to a move to the London Stock Exchange, where Autonomy joined the FTSE 100 of top UK-listed companies.

Lynch’s triumphs led to him becoming a science adviser to David Cameron when he was prime minister and a non-executive director of the BBC, as well as receiving an OBE in 2006 for services to enterprise.

However, while Autonomy impressed HP enough to pay more than $11bn for the company in 2011, it only took a year for the US computing giant to take an $8.8bn writedown on its acquisition, saying it had discovered “serious accounting improprieties” at the UK company.

Lynch had effectively been involved in defending his reputation ever since – with the legacy of the claims continuing to have ramifications despite the entrepreneur always denying the allegations of wrongdoing.

Autonomy’s former finance director, Sushovan Hussain, was sentenced to five years in prison in the US after being convicted in 2018 of fraud in relation to the HP deal.

In 2022, Lynch lost a civil fraud case brought by HP in the UK, during which it was said that the businessman exerted control over Hussain and that it was inconceivable that Autonomy’s founder was unaware of the fraudulent practices alleged to have taken place at his company.

Mr Justice Hildyard, the high court judge in the case, had been due to rule on HP’s claim for $4bn in damages and had said the amount he intended to award would be much lower. Lynch had said he intended to appeal against the ruling.

At the companies he ran, Lynch is said to have put his own personal stamp, indulging his penchant for James Bond. Conference rooms were reportedly named after Bond enemies, such as Dr No and Goldfinger, and Autonomy even had a piranha tank in the atrium, in a nod to the 007 caper You Only Live Twice.

This professional portrait of Lynch seems slightly at odds with what is known about him personally: married, with two daughters, he was reported to spend his spare time building model railways and breeding koi carp.

Since being acquitted in the US, he had said he planned to address the imbalance he perceived in the extradition treaty between the UK and the US. “It has to be wrong that a US prosecutor has more power over a British citizen living in England than the UK police do,” he said.

He and his wife, Angela Bacares, who was reported to have been rescued from the Bayesian, were said to be worth £500m in this year’s Sunday Times Rich List.

One of Lynch’s daughters, aged 18, is also understood to be among the four Britons missing after the yacht sank. Two Americans and a Canadian person are also missing.