Who would dare write a prequel to Beethoven’s Ninth symphony? Magnus Lindberg, that’s who. Two Episodes, a BBC co-commission, is a 15-minute work intended to lead up to the symphony, to complement it and to reflect some of its details: if you like, it’s a musical Louvre pyramid.

In this, its first performance, the two works were presented semi-detached: no interval, but a break for applause for the Lindberg. And perhaps the air did need to be cleared: the closing moments of the Lindberg zero in on the stark two-note interval (an open fifth) with which the symphony is to start; but until that point the London Philharmonic Orchestra had sounded restless, lush and often glittery – a world away from the elemental music with which the Beethoven begins.

It’s the iconic first gesture of the symphony – that falling figure tracing the sparest possible harmony – that is a recurring motif in Lindberg’s score, glimpsed through whirling violins at the opening, and cutting through the almost Mahlerian textures several times thereafter. Future performances might find Two Episodes standing on its own, without the symphony; but while those audiences might not get to hear the Beethoven, they will certainly think of it.

It was indeed a cerebral performance of the Ninth symphony that conductor Vladimir Jurowski offered, characterised by careful tempos and long, precisely graded phrases rather than exuberance: head over heart. Yet the final movement, well sung by the London Philharmonic Choir and a solo quartet led persuasively by baritone Christopher Purves, offered joyous if measured release.

• The Proms run until 10 September.