Before the London Sinfonietta was established fifty years ago there wasn’t any other ensemble in the UK specifically set up to promote and perform the works of living composers. The idea that such a beast could survive and thrive for five decades in the commercial world of concert promotion must have seemed an impossible dream. However, this is what has happened. With the help of generous backers, the Arts Council and a loyal and interested audience, this celebration of those fifty years was a well-deserved pat on the back for this valuable institution.

Fittingly, the concert showcased the older work of the modernist composers and, in the second half, a gaggle of premières. Three conductors and a range of performers from the orchestra shared the performing honours.

The evening kicked off with a perky fanfare by Sir Harrison Birtwistle called The Message scored for trumpet, clarinet and side drum, which he composed for the group in 2008. Next up was the Octet by Stravinsky from 1923, one of the composer's most important works, managing to perfectly combine the Russian elements of his early style with the neoclassicism that was to become so important for the next 30 years. Its angular austerity and playfulness seemed to set the tone for so much music that was to follow. It was played here with authority and easy virtuosity, conducted with precision by David Atherton.

With the addition of a few more players, the Sinfonietta moved onto the Chamber Concerto from 1968 by Ligeti. A work that was standard fare for the orchestra in their early years, this performance, also conducted by Atherton, demonstrated their high level of expertise in tackling the most challenging of technical demands. Ligeti’s crepuscular world of polyrhythmns and tone clusters was ideally captured.

After the interval the first of the commissions was a short piece called River Above by Deborah Pritchard. Scored for solo saxophone and thoughtfully performed by Simon Haram, it used a more conventional tonal idiom than anything we’d heard so far. It was notable for it’s sense of poetry and for the beautiful fading final bars.

Next up was Formations by the prodigiously talented Samantha Fernando. Scored for a larger chamber group, it is a 12-minute piece of delicacy and subtle colours, superbly brought to life with Vladimir Jurowski at the helm. It came across as an attractive piece with an original voice behind it and it was crowned by a passage near the end which introduced a faster flowing motion which opened out into a new perspective most effectively.

Hans Abrahamsen’s left-hand piano concerto, Left, alone, was the major première of the evening. Abrahamsen has been commissioned many times by the orchestra since its earliest days and it has been an important advocate for his work. This evening the commission came from elsewhere but this was the London première. Tamara Stefanovich was the sensitive soloist, dealing with all the technical and expressive demands that could be thrown at her. The work is in two movements which subdivide into three sections. These sections range from the rhythmically defined and complex, to filigree polyphony and to the very sparse. The overall atmosphere of the piece was magical with gossamer textures through most of its length. Something about the celebration of the evening didn’t quite fit with the will-o'-the-wisp nature of the piece and it will probably take another hearing to get to grips with its internal impetus. George Benjamin conducted with perception.

The evening ended with a compilation piece called Encore. To sum up the ethos of the band, fourteen composers were approached to provide tiny miniature variations on a theme by Purcell, showcasing the orchestras principal players. All this was masterminded by John Woolrich who provided the bookend pieces. The composers included Poul Ruders, Julian Anderson, Detlev Glanert and Birtwistle himself, with a host of younger composers. The idea was a good one but it proved to be far too long and disjointed, despite all the energetic efforts of the Sinfonietta and Jurowski again. With the addition of two people wandering around the stage with exclamation marks, it wasn’t quite the amusing collaboration that it was intended to be.