The way in to the venue is a nondescript entrance beside the PeckhamPlex. There’s a bouncer in attendance and some heavy-duty metal barriers such as one might see at a demo. We ascend a grubby narrow staircase to a vestibule painted floor to ceiling in bubblegum pink. There are more stairs (the lifts haven’t worked for years), and a lot more pink paint, and helpful people in Bold Tendencies t-shirts directing the punters, some of whom look distinctly relieved to have arrived safely at their destination. The BBC Proms banner reassures us that we’ve come to the right place. Meanwhile, Bold Tendencies staff issue us with wrist bands, as if we’re attending a secret rave.

As part of the ‘Proms At...' element of this year’s festival, the Proms moved out of its usual plush crimson comfort zone of the Royal Albert Hall and headed down to Peckham in south-east London for two concerts given by the Multi-Story Orchestra in a disused car park. It’s home to the orchestra and also Bold Tendencies, a not-for-profit commissioning organisation, which has transformed the multi-storey car park through its annual summer programme of cultural and artistic events, and a refreshingly relaxed, accessible approach.

At a time when those inside and outside classical music are questioning how music is presented, how long concerts should last, and how to engage younger audiences, the Multi-Story Orchestra approach seems totally in touch with the Zeitgeist, and its events have received wide praise. The orchestra is comprised of young musicians, dressed casually, while the audience sit on folding chairs (if you arrive early enough), benches or wooden stools. For this concert, the audience was pretty diverse too, which was encouraging.

For those of us more used to the highly refined atmosphere of London’s finest chamber music venue, a brutalist concrete lump with low ceilings and unremittingly grey walls cannot possibly be a good place to hear music, whatever the genre. The acoustic should be appalling, a brisk wind slices through the performance space, riffling music, which is pegged to the music stands to stop it blowing away, and the music is regularly interrupted by rattling trains and the sounds of the street below. How appropriate then to hear works by Steve Reich, a composer whose music connects art and urban life and culture with its drive, repetition and asymmetry, in this gritty, urban venue.

The concert opened with Vermont Counterpoint (1982), a work for amplified solo flute and 10 recorded tracks played on flute, alto flute and piccolo by Hannah Grayson. The tone of the flute is so consistent throughout its range that crystal clear lines and motifs weave in and out of the foreground, bouncing around the concrete walls, while its rhythmic shifts are subtle and understated. The resulting texture was surprisingly varied, quite mesmerizing in its fluctuating colours and patterns. At times, Hannah’s flute sound resembled birdsong, brightly chirruping in the concrete jungle.

Eight Lines, composed in 1979, is scored for two pianos, two or four woodwind players, and double string quartet. The pianos create a pulsating motor-like ostinato, over which gentle waves of strings hover while flute and piccolo play longer, brightly-wrought melodies. The inspiration for the piece came from the composer’s studies of Jewish “cantillation”, ritual chanting from the Torah. The piece is scored in five sections but the boundaries between them blurred which creates a sense of ambiguity and allows the work to be enjoyed as a continuous flow. The orchestra was highly amplified with thickets of microphones but in spite of this, the sound was clear, vibrantly coloured and highly textural with a particularly warm sound in the strings.

In Music for Large Ensemble (1978) the orchestra was swelled by marimbas, xylophones, a vibraphone, double basses, saxophones, trumpets and two female voices. As in the previous piece, the pianos create a continuous ostinato, together with the percussion, and the music is scored in sections containing rapid short phrases which stretch out into longer lines, combining contrapuntally with other melodies before retreating back again. The orchestration, with key changes every few minutes, creates a large palette of sonic colours, while vitality and precision combine with ethereal sonorities to bring an infectious joyfulness to the music. Its incessant pulse and spooling circles within circles has the effect of a perpetuum mobile which became more obvious as the musicians settled into the repeating rhythms and motifs. When it ended, it was as if someone had simply flicked a switch off.

Throughout the performance, the music was punctuated by trains passing close by, their rattle and hiss adding an extra layer of rhythm and melody. Despite the casual attire of the orchestra and relaxed atmosphere, this was a committed performance of vibrant energy and enthusiasm by the Multistory Orchestra and conductor Christopher Stark. I do hope the Proms returns to the Bold Tendencies Peckham carpark in 2017, for this approach, combining an unusual venue with extremely high-quality music making, creates an exciting and engaging concert experience.