Laid low by a bug, Daniel Harding had to withdraw at the last minute from conducting the LSO last night. Booked as the soloist, Leif Ove Andsnes stepped into the breach to lead Mozart’s Piano Concerto No 20 from the piano, as the composer would have done. His unruffled keyboard technique and unimpeachably neat phrasing betrayed no sign of hasty preparation. Unfortunately they also barely scratched beneath the surface of a dark and troubled work that grabbed Romantic imaginations at a time when so much other Mozart was brushed off as Rococo plasterwork.

Last and most imposing of Bruckner’s completed symphonies, the Eighth invites and frequently receives architectural comparisons. Such talk of pillars and cathedrals could only be wide of the mark in the wake of this unconventional, beautifully prepared and deeply humane performance by the London Symphony Orchestra and their principal conductor designate, Sir Simon Rattle.

Some of us have waited years for this. The opportunity to see Schumann’s largest, most ambitious work was not to be missed. For this most literary of composers, setting the Alpha and Omega of German poetry was a labour of love, which he undertook in reverse, but with progressively less reliable inspiration. From the grandiose bluster of the overture, composed last, you would be hard pressed to anticipate the sublime heights of the third part, composed by Schumann in a wake of elation shortly after completing The Paradise and the Peri.

How can an orchestra perform the music of the future? This was the question posed by Francois-Xavier Roth, congenial maestro and charming educator, as the standard concerto for platform arrangers played out behind him on the floor of LSO St Luke’s. Roth had just offered one confident answer to the question, with the first performance of Dr Glaser’s Experiment by Darren Bloom.

Brahms: Violin Concerto, Bartók: Violin Concerto No 1 Janine Jansen (violin) Orchestra dell'Accademia Nazionale di Santa Cecilia, London Symphony Orchestra/Antonio Pappano (Decca)

If the London Symphony Orchestra sounded simply magnificent in this programme of 20^th century French music, it was their restraint that caught the ear rather than the demonstration of an orchestral engine at full throttle for which they are justly renowned. Tonal refinement and fastidious attention to detail were the key signatures of the evening, as they had been for Debussy's Pelléas et Melisande at the weekend.

Debussy’s Pelléas et Mélisande is a drama played out in shadow. Shine too bright, too unyielding a directorial light on it, and the delicate dramatic fabric – all unspokens and unspeakables – frays into air. Just over a year ago, director David Edwards and the Philharmonia Orchestra gave us a semi-staging of exquisitely allusive simplicity, leaving the music to fill the gaps between symbol and emotion.

So the feasibility study for the new concert hall – The Centre for Music – has finally surfaced, a little later than planned. It’s being greeted, generally speaking, as if it’s to be the next London Olympics. “A global beacon,” declares the Evening Standard... Nicholas Hytner (he who said that building the Southbank Centre extension would spoil the view from his National Theatre) compares it to Tate Modern, which he says enlarged audiences for other visual arts rather than taking them away. This should, he says, be “a Tate Modern for music”.

The musical future looks bright indeed, at least from my perspective. There are more classical concerts than ever going on across the UK on most days of the year, so who can know with any authority what might have been missed? Yet each of theartsdesk’s classical music writers has a special take on the events of 2015, and part of mine has been the special privilege of following a trail of younger players in out-of-the-way places.

Imagine knowing Hamlet as a four-act play, or The Ambassadors without its bottom third. Imagine  Mozart’s Requiem as a torso that halts eight bars into the Lacrymosa, or Mahler’s Tenth as the lone Adagio (as, indeed it too often appears). We might admire them all the more for what we ached to feel whole as their creators intended.