Mike Lynch, the British tech entrepreneur on trial over an alleged multi-billion dollar fraud, is in line for a £300m payday from the US takeover of cyber security company Darktrace.

The business is to be bought by private equity firm Thoma Bravo for £4.2bn in a deal that will deliver a financial boost to Mr Lynch, who owns almost 7pc of the company along with his wife Angela Bacares.

They have sold down their stake significantly in recent months but their holdings are worth £298m under the $7.75 (£6.20) a share takeover price.

Mr Lynch, a founding investor in Darktrace and former board member at the Cambridge based company, is in the middle of a US criminal trial over the $11bn sale of his technology company Autonomy in 2011.

Mr Lynch criticised the prospect of a Darktrace takeover two years ago when Thoma Bravo first considered buying the business. At the time he said US authorities’ “vindictive pursuit” of him had depressed the company’s share price and left it vulnerable, adding: “Another bright light in the British tech scene will be lost.

“The UK needs to stand up for its entrepreneurs and protect its economic and legal sovereignty, not be bullied by US interests.”

He did not comment on the sale on Friday.

Mr Lynch and Autonomy’s former finance director Stephen Chamberlain are six weeks into a San Francisco trial over fraud charges that can carry decades in prison. Both have pleaded not guilty and Mr Lynch is expected to testify in the coming weeks.