Few would claim that Nikolaus Harnoncourt was an incurable romantic but listen to his Mozart and you do begin to wonder. Not that I object. The ‘Jupiter’ (Symphony No. 41 in C, K.551) is my all-time favourite symphony, a majestic call to arms with an andante cantabile that equals the parallel movement in the great G minor String Quintet for pathos and expressive intensity. Under Harnoncourt, repeats are generously observed. The martial first movement on Otto Klemperer’s fine stereo ‘Jupiter’ is paced identically to Harnoncourt’s with the Royal Concertgebouw Orchestra (in Nikolaus Harnoncourt: Mozart Symphonies, Serenades, Overtures on Warner Classics 5419736074, 15 cds, c£52.00, released on 25^th August) but because of the long exposition repeat, timings-wise, Klemperer’s first movement ratchets up a modest 9:18 as opposed to 13:21 on Harnoncourt’s version. The repeat is significant because the dramatic, pendulum-style development section (from 8:54) sounds even more like a significant musical turning point than with Klemperer.

The muted slow movement again has its first half repeated (NH’s 11:37 as opposed to OK’s 9:08) which compared with Klemperer’s seems so much more personal (certainly more dynamically shaded), those pained sforzando chords tailed by breathless semiquavers (from 1:30) truly reminiscent of the Quintet.

But it’s the finale that really benefits from the repeats (6:47/11:24), Klemperer marginally – just marginally – slower while Harnoncourt emboldens his battling brass and drums and doesn’t miss a trick when it comes to sending an added electric charge through Mozart’s dazzling contrapuntal lines. It’s a real tour de force. Try the opening: gentle at first, then wow! the initial fortissimo onslaught packs a fair wallop, and on it goes, one celebratory passage after another, and when we reach the thrilling coda at 10:22, with Mozart OD’ing on counterpoint and the superbly recorded Royal Concertgebouw playing magnificently …. nothing quite like it. Certainly not the early Classical early symphonies that follow straight afterwards (Nos. 44-46, but don’t let the ‘late’ numbering fool you), trimly played by the period-instrument Concentus Musicus Wien, appealing for sure but slim pickings after the epic ‘Jupiter’.

You’ll encounter a number of these early works throughout the set, but the pairing of the ‘Linz’ and ‘Prague’ Symphonies – total timing: 78:05 – stands alone, largely because the first movement of the ‘Prague’ falls only a few seconds short of 20 minutes. Again, Klemperer and Harnoncourt run neck-and-neck tempo-wise in the Allegro, but the repeats situation means that Klemperer’s Adagio-Allegro first movement runs to 10:54, in comparison with Harnoncourt’s more generous timing and there are parallel contrasts with the second and third movements, too. Having interviewed Harnoncourt on a number of occasions it didn’t occur to me to ask him about his views on Klemperer. Now I wish that I had.

The ‘Paris’ Symphony’s rocketing opening bars and the way the music afterwards builds are mightily impressive and yet both here and elsewhere in the set Harnoncourt virtually never rushes his fences, which benefits in particular the dramatic key change at around 3:44 into the first movement. You sense that his approach is dictated by a combination of love and respect.

And yet when urgency is required Harnoncourt delivers. His driven tempo for the molto allegro first movement of the great G minor Symphony (No.40, K. 550) is marginally more urgent than Wilhelm Furtwängler’s famously swift performance with the Vienna Philharmonic from 1948/9 though some may baulk at the way Harnoncourt controversially fragments the argument at the start of the finale’s development (3:57). Even now, after many years of listening to Harnoncourt conduct this work, I can’t quite get used to the disjointed effected of his interpretation at this point. But when it comes to the ‘Haffner’ Serenade, a sort of extended violin concerto, memorably recorded with Staatskapelle Dresden (the soloist – Thomas Zehetmair I believe – isn’t credited), all comes right again. This is one of Mozart’s loveliest large-scale orchestral works, commissioned by Sigmund Haffner the Younger for use in the course of the festivities before the wedding of his sister Marie Elisabeth Haffner and her intended, Franz Xaver Spaeth. The andante second movement vies with the best of the violin concerto slow movements for warmth and profundity while the delightful Rondo fourth movement is probably best known in Fritz Kreisler’s arrangement for violin and piano. Harnoncourt and his players do the work proud, as they do (from wherever) throughout this entire set (there are many more works included than the ones I’ve mentioned). No matter whose Mozart you have on your shelves Harnoncourt’s will be well worth adding to them. As well as being a real original he was a formidable musician with a heart, the like of which is becoming rarer with each passing day.