The good thing about this film, and its subject, is that no one mentions the words “national treasure”. Labour MP Dennis Skinner hasn’t mellowed much. He’s as difficult and bloody-minded as ever – and just as opaque. Daniel Draper’s docu-portrait of Skinner is affectionate and respectful; it takes us back to Skinner’s Derbyshire roots, showing us the ex-miner of granite integrity, still an MP at 85, still working hard in the Commons long after the likes of Cameron and Osborne have flounced.

Skinner fought fierce and wounding battles in the 80s: the sword did not sleep in his hand throughout the miners’ strike of 1984-85, and the film rightly dwells on that – though dealing rather more quickly with the inglorious infighting over Militant in the Kinnock years. Skinner’s finest hour was arguably filibustering Enoch Powell in parliament to prevent a ban on stem-cell research: a glorious triumph which perfectly combined his talent for anarchy, love of mischief and knowledge of Commons lore.

This movie is silent on many subjects. For understandable, high-minded reasons, it does not talk about Skinner’s marriage and how that came to an end. Asking him about that might be tabloid prurience, although it would have shed light on Skinner the human being.

Elsewhere, despite a brief admission that like most on the Labour left, he voted against Europe in 1975, there is nothing on Brexit, the most important UK political issue of our times. And weirdly, little or nothing on what he thinks about Jeremy Corbyn. Surely he is excited to have a real socialist as party leader – and the prospect of a socialist government, the first of his lifetime? Skinner won’t be drawn, perhaps because of his reluctance to endorse the over-dogs and the bigwigs, even on his own side. Draper’s film is at its most tender when it shows Skinner’s love of nature, a figure of almost Buddha-like serenity as he contemplates a tree.