Pearls of great price polished by Rattle and the London Symphony Orchestra

An éclat is a glow, a source of light; also by association a show of success. Pierre Boulez translated both meanings in his Éclat of 1965, with a bold display of performative and intellectual brilliance, scored for 15 musicians (surely an act of updating and one-upmanship on Schoenberg’s 15-strong instrumentarium for his First Chamber Symphony). A 16th performer is on stage: the conductor (Boulez himself originally, of course), to whom is given considerable licence as well as responsibility in holding, pausing and guiding the shards and beams of sound that shoot out from the ensemble in all directions. Especially when its constituent elements are not concentrated in a knot of players but scattered across the platform in a vestigially orchestral layout, as the members of the London Symphony Orchestra were last night at the Barbican.

This is how Sir Simon Rattle likes to do Éclat, just as he brings out the potential for seamless continuity over contrast in shaping its A-B-C-B-A arch form, at a certain cost to the halting mystery and Bartókian intimacy of the work’s central, still nocturne. The grand laissez vibrez final gesture is also Rattle’s own, consonant with his approach to other pieces of “conductors’ music” such as Brahms and Mahler symphonies. If it is possible to conceive of a persuasively Brahmsian performance of Boulez, this was it.

Around the central point of Boulez’s twanging cimbalom, the ranks of the LSO then swelled to Mahlerian dimensions for the first performance of the Interludes and Aria extracted by Sir George Benjamin from his 2018 opera on the life and depravations of Edward II, Lessons in Love and Violence. Benjamin has written for very large forces before, notably in Sudden Time (1993), but the sensual extravagance of his operatic writing is a recent development. So too, perhaps, is the overt admission of elements in his make-up as a composer that were always there, swirling beneath meticulously polished surfaces.

Now the Messiaen of St François’ stigmata comes out in the first of the six interludes, then the shadows in the cave under the cliffs of Debussy’s Pelléas in the second. Wave upon wave of Bergian, expressionist release crashed over the orchestra after the aria, sung by Barbara Hannigan as Isabel, the queen neglected in favour of the king’s adviser and lover Gaveston. Isabel gives a class in aesthetics as she wantonly dissolves a pearl in vinegar: “The beauty of the pearl is not what the pearl can buy”. We were not so far from the world of Der Rosenkavalier, when Hannigan caressed a luscious melisma over the “slow radiance” of Martin Crimp’s text, and the controlled sensuality of the moment was worthy of Strauss and Hofmannsthal.

A concert in which each work has been prepared just as much as it requires, not suffering exigencies of rehearsal time at the expense of its companions, is a rare and special event. Yet Brahms’ Fourth Symphony after the interval more than met the exalted standards set by the first half. Each gesture felt illuminated, every phrase deepened, by Rattle’s four decades of living with the piece. A tiny example, in the last two bars of the first movement, which usually goes out in a blaze of obstinate glory: the face set against the wind wore on this occasion a more sullen countenance from slightly muffling the timpani. Over and above such minute calculations, a full-strength LSO dug into each bar, played out, and filled the hall with woodland charm one moment, resolute sinew the next. It could be done differently, but not better.