Now we can hear how Shostakovich’s Fourth Symphony might have begun. Anyone present at Mstislav Rostropovich’s unforgettable Shostakovich Festival at the Barbican with the London Symphony Orchestra in 1998 will remember his brief and fractured address to the audience just prior to the performance of the Fourth. And then this: eight minutes of hitherto unheard music starting in no man’s land, a solo viola roaming aimlessly, a brusque Allegro going nowhere – literally. Shostakovich puts down his pen mid-phrase and thinks better of it.

And so begins the Fourth Symphony as we now know it – with a thunderous march for the dispossessed. ‘A Soviet artist’s reply to unjust censorship,’ he might have dubbed it, for this was music written in the wake of the scandalous Lady Macbeth of Mtsensk and we all know how Stalin’s disapproval of that cost the composer dearly. But history has come to regard the Fourth as the work at the crossroads of Shostakovich’s symphonic development and to have it coupled, as here, with the Fifteenth and final Symphony is to have the answer, I think, to at least one of the musicological riddles that this last will and testament poses. More on that anon. But first, thanks to Andante (and, of course, BBC Radio 3) for a beautifully presented and documented album. The performances are not bad, either.

The rampant, combative, defiantly ironical Fourth – the symphony Shostakovich withdrew under political pressure – is like a clearing house for the illicit imaginings of his youth. There’s an angry young man in the making here. The flabbergasting fugue which passes for a climax to the first movement development (and that’s stretching a point) is like the lid coming off the pressure cooker. Well, it is here. And the ironies – so well pointed by Rostropovich and the LSO – are the subtext to a deep and abiding disquiet. What of the furtive and funny Scherzo, with its spookily percussive shake, rattle and roll ending? What of the circus antics of the finale (anarchy with a smile) and the attempt at hollow victory just prior to the eerily indeterminate close? There’s a lot of Mahler in the mix: the grumbling string ostinato which pulls us towards the terrible disharmony of that last rolling climax is straight out of the Resurrection Symphony. How unsettling is that?

Another bonus here is the Five Fragments for orchestra, written around the time of the Fourth – cryptic shavings off the same block. But if you think them elliptical, what is to be made of the Rossini and Wagner quotations peppering the Fifteenth? Forbidden fruit from the Soviet era? Flippancy and morbidity (the Wagner quotes are all death-related). There’s more Mahler, too – the Third Symphony – in the trombone orations of the second movement, wonderfully played by the LSO principal. And noble, harrowing climaxes. But then right at the end – remember that spooky percussion from the scherzo of the Fourth? – it’s back. And if that’s not Shostakovich having the last laugh I don’t know what is. They thought they could silence him. They thought wrong