The films Leonard Bernstein made for Alistair Cooke’s Omnibus programme between 1954 and ’58 are as fundamental to understanding his burgeoning legend as West Side Story or the New York Philharmonic, and it’s a pity opportunities to see them have been limited. But five decades later here they are. Bernstein’s Don Draper suits and the granular black-and-white picture quality are very much of their time – but in inverse correlation to the great man’s perpetually contemporary insights.

There were seven Bernstein Omnibus films. For the first he demonstrated how Beethoven settled on a definitive version of his Fifth Symphony by having the Symphony of the Air play through Beethoven’s sketches, and a blueprint was set for the series. Each film opens with Bernstein establishing his line of investigation – you think jazz is a primitive art form, well you’re plain wrong, and here’s why; you think an orchestra could stay in time without me, you’re probably right, but here’s what a conductor really does; you reckon Bach is dull, well I empathise, but now listen to why I think he’s great.

Instinct brought me to the jazz film first, as Bernstein drills inside what he calls “the innards” of the music. A jazz band performs wayback swing standard “Sweet Sue” in a square four so listeners can subsequently hear syncopation in action: then as Dixieland, bop and in a Third Stream arrangement to show how the funk moved on. Transforming a rhymed couplet from Macbeth into a blues, Bernstein shines a light on the universality of the 12-bar form; the film climaxes with the first performance of his Prelude, Fugue and Riffs.

The Introduction to Modern Music film turns out to be a dry run for ideas Bernstein developed more fully during his 1971 Harvard lectures, and I found it strangely poignant and revealing. Bernstein twists himself into a pretzel to diligently unpick at how Schoenberg’s serial revolution evolved out of tonality, via Wagner, to put a bomb under the usual emotional triggers. But we know about Bernstein’s divided loyalties. He recognised the weighty consequence of serialism and didn’t much like it; but he wasn’t going to indulge in intellectual laziness by dismissing it. He signs off with a call to action: “Be glad…Modern music is your music.” A brilliant survey of American musical theatre and an ardent complete Handel Messiah from Christmas Day 1955 complete the package. Five stars. If we had them.