During the first half of this London Sinfonietta concert, I scribbled the phrase 'Lightly anarchic streak' in my notes, referring to the formal daring and the conspicuous rock music influence evident in various pieces. During Martin Creed and his band's second-half set – specifically, during a song whose lyrics were, in their entirety, 'B; B sharp; B flat; B natural', and which was accompanied by a faux-modernist black and white projection of a photo of a naked man, into whose backside the camera periodically zoomed – I realised that describing the first half's essentially rather proper repertoire as 'anarchic' would be approximately as narrow-minded and dull as describing a bottle of wine as 'subversive'.

The first half was business as usual for a London Sinfonietta gig, but the second definitely wasn't, and the contrast between the two was so ludicrously extreme as to be extremely funny. Things were rounded off by a composition for the orchestra by Martin Creed, a Turner Prize-winning artist, which hardly rivalled any of the first half's works in terms of 'pure' compositional quality but which I don't think was really meant to. It was, at any rate, food for thought, and fascinating food for thought at that.

Creed, contrasting the Sinfonietta's strict concert-black attire with an outlandish cardigan which spoke of 1970s children's TV presenters, performed a set of miniature 'conceptual' numbers with his band in the second half, occasionally alongside rather rude videos featuring nudity and vomiting. Song lyrics ranged from the refrains 'I like things a lot' and 'I dunno what I want' to oblique but engaging recitations of the alphabet and all the whole numbers up to 100. There was also an instrumental piece: a slowly rising and then falling chromatic scale which accompanied a video of a penis whose motion charted the same trajectory. Admittedly, it all seemed a little mannered at times, and Creed's bumbling patter occasionally seemed a touch more rehearsed than it was presumably meant to, but this was still a hilarious half-hour or so and would have been worth it anyway just for his observation that 'Nothing rhymes with feelings'.

Nothing rhymes with '______', either, the name of Gerald Barry's 1979 composition for chamber ensemble which was the highlight of the first half. Ten minutes in length, '______' mainly comprises a series of rising chromatic scales, but consistently varied and skewed such that it remains completely unpredictable throughout. A weirdly large proportion of the middle of this piece is given over to a circuitous exchange between two clarinettists, and particular kudos must go to Mark van de Wiel and Scott Lygate for maintaining composure in this section, sensibly left to their own devices by conductor Christopher Austin. '______' is beguiling to the power of about 50, and in a certain rather abstract sense paved the way effectively for the concert's second half.

More inclined towards pop music in the first half were Anna Meredith's axeman and Tansy Davies' neon. The former is a three-minute solo piece for bassoon and amplification which aims to turn the bassoon into a 'wailing, riffing, 1980s electric guitar god'. This was messy but fun, and played superbly by John Orford. Davies' work is also fun, a riffing and vigorous ensemble piece which features an electric keyboard set to sound somewhere between the sounds of slap bass and a SNES. It would indeed have been lightly anarchic in other contexts, but, as it turned out, it wasn't here. Philip Cashian's Spitbite and John Woolrich's Fragment filled out the Sinfonietta's set, and though they seemed less on-topic than the other works they received strong performances, particularly Fragment, a gentle soprano saxophone solo played with poise by Simon Haram.

When the London Sinfonietta returned to the stage – after Creed's 'Thinking / Not Thinking', a two-minute, two-chord number in which 'It's G for thinking' and (assuming I heard it right) C for not thinking – it was anybody's guess what the world première of Work no. 1375 would be. It turned out to be quite an earnest piece, written for three of various different categories of instrument and featuring a wide range of pitches. It was, I think, entirely devoid of chromatic notes, and I'm sure the composers featured in the first half will be sleeping easily enough. That isn't the point though, and taking the whole evening as the rather elaborate conceptual experiment that I suspect it might have been, there was only one winner.

London Sinfonietta: Martin Creed, at Southbank Centre: QEHPaul Kilbey reviews An Evening with Martin Creed and London Sinfonietta at the Purcell Room.4