Ken Loach is among both our most acclaimed and most contradictory artistic figures: a soft-spoken, middle class, Oxford educated, leftist firebrand; a seeker after truth, who chooses to express himself primarily through fiction; a much-garlanded star of the European film scene, who appears to hold many of his industry’s excesses and vulgarities in deep disdain.

You don’t have to be a devotee of his work to appreciate the rigour, diligence and depth of this documentary account of his career, which fortuitously happens along just after his latest film I, Daniel Blake has claimed him his second Palme d’Or. And that’s not the only highly pertinent element at play here.

Among the controversies covered is the case of the 1987 Royal Court production of Jim Allen’s play Perdition, which Loach directed and which took as its subject collaboration between Hungarian Jewish Zionists and Nazis during World War II. The play was pulled at the last minute amid controversy about left-wing anti-Semitism. More surprising revelations are also in store: did even Loach’s fans know, for instance, that as an actor he understudied Kenneth Williams in a West End comic revue co-starring Sheila Hancock? Or that during a fallow filmmaking period he fed his family by directing commercials for Nestlé and McDonald’s?

More painful aspects of his personal life are sensitively dealt with by director Louise Osmond (Dark Horse), whose skilful arrangement of her material creates a multi-layered impression of a polite but hard-edged individual. Since so much criticism of Loach paints him as a shrill activist rather than an artist of depth, it’s perhaps a slight loss that this film features scant analysis of his films as art, rather than as social commentary. However, it certainly works as a clear-eyed tribute to a unique career, and to the particular decades in British film and politics that it has spanned.

Selected release from Fri 3 Jun.