Fifty years ago, the LSO and Ole Schmidt gave us the first complete recording of Nielsen’s symphonies, braving power cuts and an unheated church. Even today, the sense of discovery and risk outweigh the unvarnished nature of the ensemble and recording quality. Ten years on, Danacord transferred Danish recordings from the 1950s by three conductors well acquainted with the tradition of Nielsen’s own performances: a reference set that no Nielsen enthusiast (or conductor) should pass over. In 1988 the San Francisco SO and Herbert Blomstedt offered unimpeachable playing, first-rate recording quality and comprehensive musical understanding, all of which have more than stood the test of time. Most recently, the Danish National Symphony under its present chief conductor, Fabio Luisi, re-entered the field, with accounts that rival the all-time finest. The quality of playing and recording is stupendous, as are at least three of Luisi’s interpretations (Symphonies Nos 3, 4 and 6).

Forced to keep just one of the above – Desert Island Discs-style – I would temporise and clutch each one fiercely to my bosom. Apologies, too, to devotees of any of the dozen or more estimable complete sets I haven’t mentioned but which have helped put Nielsen on the map in a way that would have seemed inconceivable back in 1974. And now Naxos – or someone pitching to them – has had the brilliant idea of following the Danacord precedent through to the present day, featuring the orchestra that knows Nielsen’s music best (and in which he himself was a violinist for 16 years) with six principal or guest conductors from 1965 to the present. My arms have become even fuller, my grip even tighter.

Irrespective of the quality of performances, the documentary value of the set is high, not least thanks to the essays on the music and the performances (Andrew Mellor) and an eyewitness account by orchestral violinist Troels Svendsen of Bernstein’s 1965 visit to conduct the Sinfonia espansiva in Copenhagen, timed to coincide with the centenary of the composer’s birth.

I would caution against reading too much into the evolution of the Royal Danish Orchestra itself. Certainly, the woodwind solos have become more refined over the years, with no loss of character. On the other hand, the slight thinness of the string sound, which might be held against the 1950s performances, still resurfaces from time to time. It doesn’t in the latest Luisi set, but it does to a degree in the 2022 Naxos version of the First Symphony. Thomas Søndergård (formerly a timpanist in the orchestra) offers a reading that is forthright yet human, dramatic yet poetic. His Andante is on the slow side but not as lethargic as Luisi’s (a rare blot on the latter’s interpretations) and is amply redeemed by the empathy and sense of wonder it radiates. Each movement offers delicious profiling of phrasing and articulation, and the enthusiasm that propels the finale to its conclusion is almost palpable.

Vedernikov’s Four Temperaments, recorded in September 2020, the month before his death, is rather hit-and-miss. Launched with terrific vigour, the ‘Choleric’ first movement sags whenever Nielsen specifies tranquillo, while the second movement is more soporific than ‘Phlegmatic’, and the actual slow movement – the ‘Melancholic’ – also drags. The ‘Sanguine’ finale is boisterous enough but topped off by an unconvincingly precipitous stretto, as if trying to emulate what Bernstein had done so brilliantly 55 years earlier in the finale of the Espansiva.

Pace Troels Svendsen’s note, it was Bernstein’s incandescent CBS recording of the Fifth Symphony that put Nielsen on the international map. That in turn occasioned the award of the Sonning Prize and the invitation to Copenhagen. Coming to Bernstein’s Espansiva in order of composition rather than performance, you can almost feel the musicians moving to the front of their seats, buckling up and preparing for the music to course through their veins. As the booklet explains, in rehearsal Bernstein was in effect learning the piece from the orchestra. But in performance his own creative personality took over. He wouldn’t have needed to tell the players anything about the music’s embodiment of the Life Force, because he himself embodied it, as we can see as well as hear in the video of the public performance, which followed the day after the studio recording and is now viewable on YouTube. Objectivity demands I note that the soprano soloist is not the most mellifluous or the best tuned. And Bernstein’s finale may be a little too regal for its music’s own good. But I’d forgotten how much love there is behind it.

Most startling, to me, is Rattle’s electrifying account of The Inextinguishable: a good deal more ‘incendiary’ (Mellor’s apt description) than his EMI studio version with the CBSO, which itself was pretty impressive. The first movement has an irresistible forward momentum, and although ensemble wobbles at the beginning of the third movement, that’s just a heat-of-the-moment thing. The finale is nothing short of sensational, in the best sense. Luisi is terrific here too, by the way, as he is in the Espansiva.

Sadly, the less said about Michael Boder’s trudge through the first movement of the Fifth Symphony, the better. His second movement is back on track, but that’s small compensation. Unfortunately, Luisi’s second movement is uncharacteristically circumspect, which leaves the classic 1962 Bernstein still unsurpassed. Berglund’s Sixth is remarkably straight and objective: rich in detail but a little short on character compared to, say, Blomstedt or Luisi. What’s interesting is how much of the symphony’s complex psychology survives this rather severe treatment.

On the ‘bonus disc’ the Clarinet Concerto certainly earns its place. The accompaniment is beautifully balanced and as sharply profiled as the moments of calculated ungainliness in John Kruse’s superb solo playing. Michael Schønwandt’s Maskarade Overture might seem an odd choice to follow, not least because the opera house acoustic is unsympathetic and the performance, initially a little scrappy, is of the truncated version leading into the first scene of the opera, rather than Nielsen’s rip-roaring concert version. Still, the spirit of the thing is spot on: taken at a terrific lick and heart-warming where it needs to be.

In sum, then, this is an issue as attractive as it is instructive. No individual set can possibly say everything there is to say about Nielsen. But to experience this one – and the same goes for any of my listed comparisons – is to fall in love with the symphonies all over again.