Harold Hamm, billionaire oil tycoon and erstwhile Donald Trump confidant, stands in a crisp suit at the head of a long dark table in a boardroom high up an Oklahoma City skyscraper. Maps, leaflets, ring binders and papers are strewn the length of the table. With sudden alarm, I note they include articles on US energy from the Financial Times.

“Mr Hamm is ready for you — very ready,” his head of communications had told me in the downstairs lobby a few minutes earlier. She wasn’t wrong.

Hamm is America’s most famous oilman: a pioneer of the shale revolution of the past 20 years that made the US the world’s biggest oil and gas producer, lessening its dependence on Middle Eastern energy and upending geopolitical norms in the process. To legions of fossil-fuel advocates on America’s right, Hamm, 76, is the self-made hero of the country’s energy renaissance. But with a president in the Oval Office who has promised to “transition” from oil, Hamm is now in a battle to defend this legacy — and I’ve driven eight hours from west Texas to Oklahoma City to ask him about it.