Our story ends at the very top, with a fax to the White House. The campaign to spread doubt about climate change was so successful, it infiltrated the White House. In 2007, a House of Representatives Committee investigation ruled: ‘There was a systematic White House effort to minimize the significance of climate change by editing climate change reports’.

But years later, after the oil money pipeline was cut, the key groups who initiated the strategy had folded, huge swathes of the population still doubt climate change. In 2001, about 50% of Republicans thought human activity was the main cause of global warming. Ten years later that was down to just 30% or so. What happens when a Republican politician proposes legislation to tackle climate change?

From climate change to smoking and cancer, this is the story of how doubt has been manufactured. This 10 part series explores how powerful interests and sharp PR managers engineered doubt about the connection between smoking and cancer and how similar tactics were later used by some to make us doubt climate change. With the help of once-secret internal memos, we take you behind boardroom doors where such strategies were drawn up and explore how the narrative changed on one of the most important stories of our time - and how the marketing of doubt has undermined our willingness to believe almost everything.

Presenter: Peter PomerantsevProducer: Phoebe Keane