There have always been Marxists in Labour but it has never been a Marxist party (or even, by some definitions, a socialist one). Its 2017 general election manifesto was social democratic in nature, vowing to reform rather than replace capitalism. But in his speech, McDonnell couched the party’s pledge to renationalise “water, rail, Royal Mail and energy” in more radical terms: “It’s a significant development as a result of the new exploration of the ideas of Marx.”

John Mcdonnell and the rebirth of British marxism?