Anthony John Clark

Born in Blackpool, Clark's family moved to Lincolnshire and he was educated at Barton Grammar School.

After achieving his doctorate, Clark joined John Bishop's team at the Institute of Genetics, University of Edinburgh, where he carried out research into the genes in the liver of mice.

In 1985 he was appointed to the Animal Breeding Research Organisation (subsequently the Roslin Institute) where he began work in genetic modification to produce a sheep giving milk with human proteins.

Tracy, born in 1990, was the first sheep to produce large quantities of human protein, making 35g of the alpha-1-antitrypsin (used in treatment of cystic fibrosis) in each litre of her milk.

With his colleagues, he produced a sheep from which a prion protein gene had been removed, the first time this had been achieved in a large animal.