In July 1996, scientists at the Roslin Institute created the world’s first animal cloned from an adult cell.
Dolly the sheep was created in a laboratory using an adult cell taken from one sheep to fertilise an egg from another. The fused cell was then implanted into a foster mother.
It was a breakthrough in the history of genetic engineering. Researchers hoped it would enable new ways of treating debilitating diseases, but critics were worried it opened the door to human cloning.
Sir Ian Wilmut led the team of scientists.
You can watch Witness a these times on BBC World News.
Witness the stories of our times told by the people who were there.