Two questions were answered in this last concert of the 2015/2016 LSO season at the Barbican. The first a philosophical and musical one, the second being why Sir Simon Rattle has been chosen as next Music Director of the orchestra. Make no mistake the first half of this concert, featuring Ives and Beethoven, was reason enough to see why the new partnership is an exciting prospect.

The Unanswered Question by Charles Ives that opened the concert is a short but penetrating work with three elements that mysteriously interact. In this performance the muted strings and the questioning trumpet were out of sight and produced a disembodied effect. The three flutes that attempt to answer the ‘question’, with increasing agitation, were on stage amongst the orchestra and soloist waiting to play the Beethoven Fourth Piano Concerto. A swift but telling performance of the Ives tailed off to a G Major chord on the strings, magically picked up by the distinguished soloist, Krystian Zimerman, cleverly moving straight into the opening bars of the Beethoven.

And this was a performance of enormous musicality, despite a slight sluggish opening, as the soloist and orchestra emerged from the contemplative mood created by the Ives. It was in the stormy development section that the performance truly took flight. Incisive playing from the LSO created a dialogue with the inspired soloist that grew in stature as the piece progressed. The first movement of this most popular of Beethoven’s five piano concertos is one of the trickiest to bring off. An endless flow of scales, arpeggios and trills need to be produced by the soloist with ease and accuracy, while an underlying edginess needs to be sustained. Zimerman understood all of this and responded with an evenness of tone and responsiveness to the orchestra which was breath-taking.

In the short recitative-like slow movement, Rattle insisted upon a very sharply dramatic sound from the LSO strings, answered here meltingly by the soloist, using every opportunity given to him to produce a touching sweetness of tone. In the Rondo finale we saw the interaction between Zimerman and the orchestra reaching its height. This life affirming music, which still asks questions and probes depths, finds a playful and joyous path to its positive G Major conclusion and seemed to close the circle with the Ives. With Zimerman so relaxed and playful here every note sparkled beyond the constraints of technique and interpretation.

The concert ended with a full-blooded account of Rachmaninov’s epic Symphony no. 2 in E minor. This work has become a calling card for Rattle since he first recorded it back in 1984, conducting the work now without a score. The LSO sound seemed ideal for the work, particularly the rich but lean strings and Rattle’s tempo choices were generally spot on. The great climax of the first movement development was built up massive layer by massive layer with great aural depth, but the last ounce of angst was somehow missing. In the Scherzo that follows the initial tempo was fast and exciting, but this led to a loss of impetus in the lyrical passages.

The slow movement was a delight benefiting the most from Rattle’s full blooded lyrical approach. The famous clarinet solo was consummately played by Andrew Marriner and the whole orchestra seemed to be on fire here. The finale also suffered slightly from a sense of lingering too long on the lyrical, despite an overall fastish tempo that worked. The coda blazed as it should but the final impression was not as emotionally satisfying as it can be. An aural experience to savour then, but not without its structural interpretive flaws, making the work feel about five minutes too long.