Coming in from a cold and rainy October day at the end of August, it’s safe to say that the audience for Prom 55 needed some warming up. What could be better than the searing heat of Boulez’s …explosante-fixe… to get the blood flowing? Followed by the ethereal, awe-inspiring splendour of Ligeti’s Lontano and the madcap bravura of Bela Bartók’s Concerto for Orchestra, the sheer sonic immensity of this concert was a wholly welcome shock to the system. Delivered with bucketloads of panache from the SWR Symphony Orchestra Baden-Baden and Freiburg and François-Xavier Roth, this otherwise vivacious concert ended on a bittersweet note; for the SWR Symphony, this was their first and last ever Prom.

A cost-saving merger with the Stuttgart Radio Symphony orchestra is slated for 2016, and so it was that Roth, before a heartbreaking encore from Schubert’s music to Rosamunde, told the audience of the orchestra’s “great sadness”, and dedicating these fine performances to “the utopia of Art”; qualifying this, though, he added “but for the arts, we need orchestras!”. To see the musicians walk off stage hugging each other and walking off stage arm in arm was genuinely tearjerking. The loss of the orchestra that premièred Lontano and which has, for 70 years, proselytised passionately for new music will be keenly felt by the classical music world.

The emotional impact of this moving finale would have been infinitely lessened by poor performances; fortunately, any fears of that were dispelled by the very first flourish of …explosante-fixe… I found myself once again appreciating the Albert Hall’s acoustic; if there’s any music it’s truly made for, this is it. Amplified flutes whizzed and popped around the hall, the booming click of finger-pads filling the space in an almost comical way, like a mockery of the RAH’s propensity to send any disruptive audience noises flying far and wide.

With soloist Sophie Cherrier flanked by two colleagues, and three instrumental groups behind them, the uncanny immediacy of the amplified sounds, capturing even breath, gave the impression of listening to a piece from inside a gigantic flute. If any of the masses of rhythmic detail in Boulez’s scoring was lost, this did not spoil the sense of breathtaking creative outpour that characterises the piece. Boulez’s unmistakably intense creative voice sounded just as challenging as ever, and the thrill of the complex tuttis made for deeply meditative, powerful interludes, where the lights were dimmed to accompany the purely electronic music courtesy of the SWR Experimental Studio.

Lontano is a part of this orchestra’s history, and it showed. Almost every entry in the great build-up that begins the piece was magically quiet, and Ligeti’s demand that the whole piece be played “with great expression” was fully realised. The shimmering waves of the ending churned, the massed orchestra glittering fearsome with one of those perfectly horrendous chords that Ligeti knew just how to deploy.

Lontano almost presages all of the things that would go on to make Holy Minimalism so popular – a slow, meditative pace of change, clearly articulated harmonies, and austere means of expression – and do them one better, something that Roth’s reading really showed. Every change of chord told absolutely, and the perfect serenity of the atmosphere belied the rather austere means of expression. There’s no melody here, nothing to latch on to; it is music divorced of nearly all the things we look for, and yet the orchestra imbued it with incredible emotional heft. A hat-tip to tuba player Werner Götze, whose long bass note seemed heedless of the demands of human lungs, and blended seamlessly into the contrabassoon and basses.

It’s difficult to imagine a better send-off for an orchestra than Bartók’s Concerto for Orchestra. Full of foot-stamping vivacity and star turns for every section, this folksy romp is a real gift. Roth wrung the maximum effect from every moment. The second movement’s repetitive wind duets could easily obscure the myriad glitterings in the string parts, but it was to the strings that Roth paid by far the most attention; the effect was magical, trills and pizzicatos only enhancing the bravura playing coming from the back of the ensemble. Roth always kept the orchestra well-balanced, even in the most bombastic of Bartók’s tuttis, but there was fun here, too. The fourth movement’s noble, Kodaly-esque tune was full of fire and passion, and the finale was taken at a heart-stopping, breakneck pace.

All in all, this marvellous orchestra’s gifts were fully on display throughout, and the concert just went to show why this orchestra has the excellent reputation it has, and why its dissolution will be a real tragedy for the modern musical world. At least Roth and the SWR leave a fabulous legacy of innovation, and as for their short Proms history? Faultless.