A man has been convicted of blackmail and stalking in connection with a dispute involving a £1.2 million property in west London. Darren Cooper was found guilty at Inner London Crown Court of targeting Peter Gillingwater, a tech entrepreneur, and his daughter, Aimee Gillingwater, over several months in 2023.

The case stemmed from a legal battle involving Thain Kleinhentz, an NHS sexual health adviser from South Africa and husband of a sex therapist. Kleinhentz had unsuccessfully pursued a High Court claim for a £250,000 share of a west London house that sold for £1.2 million in 2015. He argued that he was entitled to this sum as the long-term partner of the property’s owner, Mark Harrison. The court ultimately ruled against Kleinhentz.

During the High Court proceedings, Gillingwater gave evidence supporting Harrison’s position. The jury heard that this prompted Cooper—who lives in Clapham, south London—to create a newspaper-style blog falsely accusing Gillingwater of drug dealing and sexual abuse. The blog also contained abusive and derogatory remarks about Gillingwater’s 28-year-old daughter, Aimee, who works as a model and singer. Cooper threatened to damage her career as part of his campaign.

Prosecutors told the court that Cooper demanded payments of £250,000, £100,000, and £80,000 in exchange for taking down the blog and removing abusive social media posts directed at the family. The harassment extended over a two-year period from 2021 to 2023, during which Cooper was convicted of stalking both father and daughter.

Both Cooper and Kleinhentz were arrested during the investigation. However, only Cooper was charged; he admitted to creating the defamatory blogs and sending threatening communications to the Gillingwater family.

Cooper, 62, was granted bail pending a pre-sentence report, with sentencing scheduled for November 27. Kleinhentz continues his role at Guy’s and St Thomas’ NHS Trust. No charges have been made against him in relation to the harassment campaign.