Graham, who wrote the hit TV drama about Brexit, The Uncivil War, starring Benedict Cumberbatch, is renowned for his even-handed approach and for avoiding revealing his own political stance.
But he has lambasted Johnson and Trump in a hard-hitting interview in which he denounces “populist” leaders.
Tossing aside his usual impartiality, Graham declared: “F*** it! I DO want to disrespect Johnson.”
The former Conservative prime minister had wasted a golden chance to set the UK on a new path, he said. Britain was crying out for new leadership – and it could come in the form of the imminent general election.
He praised Joe Biden for attempting to reverse the culture of populism” in the US while lamenting that Trump’s “narrative has taken root and it is impossible to uproot it”.
Britain had failed to “reset itself”, as it had in 1945 and 1979, Graham told the Desperately Seeking Wisdom podcast hosted by David Cameron’s former spin doctor Craig Oliver.
“Something has gone wrong in the last 10 to 15 years. It goes back to the (financial) crash in 2008. It felt like a moment when we were going to begin a new story… It just didn’t happen.
“It didn’t happen because, no disrespect to Boris Johnson… actually, f*** it! I DO want to disrespect Boris Johnson. He fumbled the ball. We have lost that moment and may never get it back.
“We are going down into levels of madness because we cannot reset the story, with characters like Trump.
“We need new characters with new stories to tell, that might be in the form of a general election.”
Graham’s outspoken views are in contrast to a previous reluctance to reveal his own political stance. He has joked in the past that some assume he is “massively” left-wing, but he has been careful to avoid being drawn.
He is more forthright in the podcast, however, arguing that politicians who attempt to “ride the tiger of fame and populism” are doomed to fail “because it is going to eat you in the end”.
“At some point, we are going to have to decide whether to reverse that culture. That is what Biden was trying to do in the US.
“The problem is Donald Trump is a more compelling storyteller than Joe Biden. His narrative has taken root and it is impossible to uproot it. You get real-world consequences.”
It could “explode” into violence, as it did in Washington in 2021 after Trump supporters stormed the US Capitol when he refused to accept losing the US election.
“I worry about it,” said Graham. “The darker side of humanity exists in all nations and cultures and is always closer to the surface than we think. We have a responsibility not to inflame those forces.”
Graham, 41, has written a series of political plays and films, including Brexit: The Uncivil War, This House, about the collapse of 1970s Labour government, The Coalition, about the Cameron-Clegg administration, Ink, about the rise of Rupert Murdoch, as well as non-political shows including a musical about TV evangelist Tammy Faye, with songs by Elton John, and Dear England, a current West End play about England football manager Gareth Southgate, starring Joseph Fiennes.
You can listen to the ‘Desperately Seeking Wisdom’ podcast interview with James Graham from Monday 12 February.