You can picture the press release now. ‘The Somewhere Symphony Orchestra is delighted to announce that it will be presenting a full cycle of the seven symphonies of Jean Sibelius in the composer’s 150th anniversary year.’ The shock, originality and artistic vision of it is quite staggering. Take the composer’s most frequently performed works – works which are also pretty regularly performed together in succession – and perform them together in succession. The supernatural significance of an anniversary year ending in ‘0’ is sure to add some sort of magical significance, isn’t it?

Well no, actually. It probably isn’t. As I wrote at the time, I’m afraid I found the procession of production revivals and operas-in-concert (just as the composers didn’t intend them) that marked the UK’s bicentenary celebrations of Wagner and Verdi in 2013 a bit of a cop-out. What you can do if you want to invest a cycle of works like Sibelius’s symphonies with some sense of contemporary relevance – to alter the course of their music into the minds and bodies of people who have heard that music a fair bit before – is programme them as the composer intended and with a conductor who has something current, valuable and individual to say. If you live in Manchester, you had the benefit of that just last year when John Storgårds conducted the seven symphonies with the BBC Philharmonic at The Bridgewater Hall. But hey, it wasn’t an anniversary year so maybe it doesn’t count…

Listening to Storgårds’s recordings of the symphonies with the BBC Philharmonic (just issued on Chandos) is a big, resounding reminder of how infinite this music’s capacity for renewal and reinterpretation really is. But when you look at the recording schedules and orchestra brochures against Sibelius’s actual catalogue of works, it throws into shameful focus just what a small proportion of his music we acknowledge the existence of. With Sibelius in particular we seem to be stuck on the symphonies to the detriment of almost everything else.

And spare a thought for Sibelius’s fellow Nordic symphonist and exact contemporary Carl Nielsen, also celebrating his 150th in 2015. In the last decade the Proms has gifted us a piece of Nielsen just five times. Unfortunately those five occasions have involved just two works: the Fourth and Fifth Symphonies, the composer’s most ubiquitous creations outside Denmark. And which of his symphonies will the Proms present in 2014? That’s right: the Fifth.

So here’s an idea for 2015, on the off-chance that there’s still time for the programmers to take any notice. If we have to have a Sibelius Symphony cycle – and when it comes to the crunch, any such event will probably be utterly wonderful if it has a communicative musician in charge – let’s have it in a city where there hasn’t been one for a few years: not London, not Manchester (maybe, shock horror, not even in a traditional concert hall at all). Or how about we leave the symphony cycle to Nielsen? That way we’ll have an all-too-rare opportunity to hear the composer’s brilliant First, Second, Third and Sixth symphonies, works that hardly ever get played.

But we can do even better than that. For Sibelius’s anniversary in 2015, let’s programme some pieces we hardly ever get to hear live – even in Finland. If we value his symphonies above any of his other creations, perhaps we can allow the rarer, seldom-heard works to inform our understanding of those seven masterpieces. Let’s hear the spellbinding cantata Snöfrid that sounds like a lost sci-fi movie score. Let’s hear the terrifying tone poems The Oceanides and Tapiola, and the Lemminkainen Suite – pretty much a symphony in itself and a score containing some of the composer’s most remarkable orchestral structures. Let’s hear the luminous Cantique and Devotion for cello and orchestra and some of the many evocative sets of theatrical incidental music.

Away from the orchestra, how about giving us some of the delicate a cappella motets like Sortunut ääni and Sydämeni laulu and dipping into the wealth of chamber music – the early E flat string quartet or one of the plethora of works the composer wrote for violin and piano. If it turns out some of those pieces aren’t worth hearing again for another half-century, fair enough. At least we’ll have had the opportunity to make the judgment ourselves.

For Nielsen, who wrote what is arguably the most fully integrated and linear major symphony cycle since Beethoven’s, let’s hear the lot in order. And how about the extraordinarily impolite First Violin Sonata, the gregarious String Quintet, the prototype Symphonic Rhapsody, the visionary An Imaginary Journey to the Faroe Islands, the deeply affecting opera Saul and David, the stylistically fascinating Opus 55 motets or the organ monolith Commotio (which is available to orchestras in Bo Holten’s imposing and uncannily Nielsenesque orchestration)?

You get the picture, and you probably have your own pet works you could add to the list. But the point stretches far beyond personal preference and to something altogether more important and significant – namely this: if we insist on programming a living art form via the arbitrary milestones that are composer anniversaries, then those milestones have to serve as opportunities for argument, reappraisal and rediscovery. If they don’t – and if the repertoire of our performing institutions continues not just to stagnate but to dwindle – our art form will look more and more like a nostalgia-fuelled curiosity, increasingly divorced from its literary, visual and cinematic siblings.