Mark Purdey

He married Carol MacDonald in 1974, a marriage that produced a son and a daughter. When that relationship broke up, he set up home with Margaret Unwin, with whom he had four daughters and two sons. They married one year before his death. He died of a brain tumour on 12 November 2006 on his farm in Elworthy, West Somerset.

In 2001 the European Commission Health and Consumer Protection Directorate-General differentiated between BSE transmission and BSE susceptibility, stating that the main problem in determining factors that increase susceptibility to BSE was the very limited data set which could not substantially confirm or deny possible factors.

His theories encouraged researchers to publish in 1999 the statistical correlations between the epidemiology of BSE in cattle, scrapie in sheep and vCJD in humans.

In his mid-twenties, he set up an organic dairy farm, first in Ireland, and later in Pembrokeshire, on which he bred a herd of pedigree Jersey cattle. He wrote on his website that he introduced semen from New Zealand, Denmark, and Canada, to produce a "high fat, high yielding, pasture-fed Jersey cow" with an ability to produce milk from a "self-sufficient arable/legume-grass rotational system with minimal reliance upon purchased in concentrate feed." In 1997, one of his cows was the highest yielding Jersey cow in the UK, with 10,150-litre lactation, after she had been sold to a conventional farm. He is reported to have enjoyed playing the saxophone to his cows to keep them calm.

His anti-establishment views, his doggedness, and his willingness to educate himself brought him some high-level contacts in the UK, including the Prince of Wales and Lord King, the former defence secretary, who regarded Purdey's work as a "classic piece of scientific investigation." It was King who, in April 1993, formally alerted the Ministry of Agriculture to Purdey's research, after Purdey forwarded King a letter from Professor Satoshi Ishikawa of Kitasato University, who wrote that Purdey's description "about Mad cows to organophosphates compounds and warble fly is exactly true."

The Telegraph writes that public support for Purdey increased after the BBC aired a documentary about his theory in 1988.

John Mark Purdey (25 December 1953 – 12 November 2006) was an English organic farmer who came to public attention in the 1980s, when he began to circulate his own theories regarding the causes of bovine spongiform encephalopathy (BSE or "mad cow disease").