Donald Trump harangued the former first minister of Scotland Alex Salmond as "Mad Alex" and accused him of being on a "march to oblivion" in a series of increasingly angry and eccentric letters about windfarms he claimed were blighting his Scottish golf courses. The correspondence with Salmond, revealed by the Huffington Post after a freedom of information request, demonstrated that Trump's tone swung wildly between coaxing and threatening as he grew increasingly frustrated with his former ally's refusal to change his policy on renewable energy.