Der Nächtliche Wanderer, first performed in 2014, is the work with which Reinbert de Leeuw – nowadays best known as a pianist-conductor – ended a 40-year compositional silence, previously broken only by a series of chamber versions and recompositions of music by Mahler, Zemlinsky, Schubert and Schumann.

The work – given its UK premiere by the BBC Symphony Orchestra under Oliver Knussen – was inspired by a Friedrich Hölderlin poem and written for colossal forces. It’s an immense, single-movement piece that revisits and reimagines the shadowy side of Austro-German post-romanticism. The nightly wanderer of the title is the owl, whose cry portends death: the score forms a long and at times disquieting confrontation with mortality.

Nagging figurations alternate with battering climaxes. Tolling bells and gongs beat out the passage of time. A piano elegy on which Wagner was working at the time of his death is rendered banal by being played on an accordion, while on tape dogs bark, a bull roars and an actor reads Hölderlin’s poem in a seductive whisper. It gets under your skin. The conducting and playing had wonderful assurance.

Its companion piece was a curiously uneven performance of Brahms’s Second Piano Concert, with Peter Serkin as soloist. Serkin’s playing was supple and nuanced, though short on the grand gestures the work needs if its combination of the intimate and the epic is to have the appropriate effect. There were problems with the piano-orchestral balance in the first movement. The andante was exquisite in its poise.

• The Proms run until 10 September.