A multibillion-dollar court showdown between Mike Lynch, Britain's leading technology entrepreneur, and Hewlett-Packard (HP) will come to a head on Friday, just as Britain decides whether or not to extradite him to the United States.

High Court Justice Robert Hildyard will outline his findings in a civil case brought by HP against Lynch for what it argued was a fraudulent inflation of the value of his company Autonomy before he sold it to the U.S. tech giant.

The ruling follows almost 10 years of bitter wrangling over who was to blame for the failure of the $11 billion acquisition, which ended up destroying multiple reputations and costing HP shareholders billions of dollars.

A year after acquiring Autonomy, HP threw out the architect of the deal which was supposed to help transform the computer and printer maker, one of Silicon Valley’s original companies, into a more profitable group centred on business software and services.

It wrote down the value of Autonomy by $8.8 billion and sought damages of around $5 billion from Lynch and his colleague Sushovan Hussain, alleging they inflated the value of Autonomy before selling it. Hussain was convicted in the United States in 2019.

Lynch has denied all the allegations and said the failure of the acquisition was due to HP's mismanagement. Autonomy was capable of searching and organising unstructured information, such as telephone conversations.

After the court verdict, Lynch is also due to hear on Friday whether Britain's interior minister Priti Patel has approved an extradition request to the United States where he faces criminal charges including wire fraud and securities fraud.

A court has given Patel until midnight on Friday to make a decision, although Lynch could appeal any ruling that goes against him. The U.S. charges carry a maximum term of 20 years imprisonment.

Lynch is one of Britain's leading tech bosses.

The 56-year-old's doctoral thesis remains one of the most consulted at Cambridge University and his success, including the around $800 million he made from his stake in Autonomy, elevated his position in Britain, giving him a place on government advisory boards.

Lynch was also central to the creation of DarkTrace, a cyber security firm that listed on the stock market last year. Lynch and his wife Angela Bacares own nearly 16% of DarkTrace, according to Refinitiv data.

(Reporting by Kate Holton; Editing by Mark Potter)