There can't have been too many concerts ever which have started with a setting of Gertrude Stein and ended with an extra-camp version of 'Ding Dong! The Witch is Dead'. The London Sinfonietta certainly broke a barrier or two on Saturday night, that's for sure. And they did it with great style, introducing the UK to three works by Austrian composer Olga Neuwirth in an 'In Portrait' concert which certainly kept the crowd guessing.

The first half, conducted by Garry Walker, featured the chamber work Five Daily Miniatures – a setting of five aphoristic snippets by Stein involving different days of the year – and ...miramondo multiplo..., for trumpet and large chamber ensemble. The second half was devoted to Neuwirth's Hommage à Klaus Nomi, a 'Songplay in Nine Fits' exploring the musical legacy of the eccentric 70s countertenor/pop star Nomi through warped orchestral arrangements of his hits. It was neatly conducted by Gerry Cornelius, and countertenor Andrew Watts may deserve a small medal for his keen, brilliant performance.

Musically, the concert was just as eclectic as its source material, ranging from neo-modernism to ironic synth pastiche. For her Stein setting, which also featured Andrew Watts, Neuwirth adopted a conspicuously modernist approach, demanding minute detail from the players and exploring a varied and slightly bizarre range of extended techniques, from stroking the sides of piano keys to having Watts slip from his falsetto into declamation. But rather than this being a flashback to either of music's two 'original' high-modernist moments (the early 20th century or the 1950s), Neuwirth took care to decontextualise. Five Daily Miniatures felt like a very synthetic creation, and the manic meticulousness of the score came across more as an ironic response to Stein's own modernist aesthetic, than as a sincere expression of Neuwirth's own artistic leanings. This was a fascinating study, but not one through which I felt I could glean a portrait of Olga Neuwirth.

Engaging again with spectres of modernism, ...miramondo multiplo... recalled Pierre Boulez both through its ellipsis-rich title (cf. ...explosante-fixe...) and its extraordinary, lush opening chord (cf. Pli selon Pli). But Boulez was just one reference of many, and there were hints of Handel and Aaron Copland to contend with as well. While I was unable to pick up on the Miles Davis 'echoes' promised to me by the programme notes, this was still not a strictly classical affair, featuring as it did several moments of near-schmalz and a Procol-Harum-esque keyboard ostinato. The demanding solo trumpet part was played with assurance and a beautiful tone by Alistair Mackie, who engaged brilliantly with the ensemble and imbued the work with a sense of dialogue. This was an engaging, if abstruse, twenty minutes, delivered with the Sinfonietta's trademark cool.

The concert's second half was markedly less recondite, and saw a show-stealing display of theatrics from a sparkly-tied Andrew Watts. Numbers sung ranged from Nomi originals such as 'Simple Man' and 'Total Eclipse', through 'Ding Dong!...', to a couple of Purcell numbers (Dido's Lament, and 'What power art thou' from King Arthur, styled by Nomi as 'The Cold Song'). All received a similar treatment in arrangement, with artfully gauche electronic effects and a deliberate skewedness to the orchestration. Watts was often asked to out-camp even Nomi, adopting a silly fake German accent to sing 'Ze Vicked Vitch' and provocatively pouting and tapping his feet.

Just as Nomi's versions transpose all the original songs into the same strange, camp space, so Neuwirth's arrangements force all the music back through a similar surrealist lens. The Purcell songs were, of course, not discriminated from the disco ones. The point, I suppose, was that everything ultimately gets fed through the same blender, and while there was a strongly entertaining element to the performance this was hardly an uplifting experience.

Because for all the camp excess, Neuwirth's irony seemed disconcertingly straight. Here were nine pop arrangements, slashed out of context and 'arted up' for the concert hall. We were not given the opportunity to appreciate Nomi's work; instead, we were restricted to gazing at its limitations. I even wondered at times if there wasn't something cruel about this radical misappropriation of Nomi. The programme notes informed that he left Europe for New York feeling 'like a square peg in a round hole'. Neuwirth hardly makes him fit in any better. Her intent may well have been to unsettle her audience, but there are warmer ways of doing so than this.

That said, this was an exemplary account of the work from the London Sinfonietta, and a confident conducting debut from Gerry Cornelius – as the first half had been for Garry Walker, also new to the ensemble. The electronics were excellently handled by Sound Intermedia, and a useful nod to Nomi was provided by some video footage arranged by De Novo Arts. I feel, though, that I still don't know Olga Neuwirth very well, even after this 'Portrait'. Hiding ironically behind Klaus Nomi isn't the best way to introduce yourself.