Sometimes obliquely byzantine but sometimes blindingly direct, the new book of essays by composer-academic Alexander Goehr (Finding the Key, Faber pounds 11.99) is the most engaging bedside book of musicology I've read for ages. And in one essay - a memoir of the so-called Manchester School in the 1950s - there's a sharp vignette of an encounter with the youthful Peter Maxwell Davies. "You compose?" asks Goehr politely. "Only when I want to," snaps the scourge of smalltalk.

Half a century on, Sir Peter clearly "wants to" all the time: his productivity is fierce, relentless, and not always destined for immortal life. But the word is good on his new oratorio Job, which gets its UK premiere next weekend at the Barbican. And last Tuesday saw the successful London premiere of his new Piano Concerto which had been unveiled a few nights earlier in Nottingham, and with the same forces: Kathryn Stott, the Royal Philharmonic Orchestra, and Maxwell Davies to conduct.

Over all this massive output, Davies hasn't fought shy of traditional forms. And yet, oddly, there has never until now been a piano concerto. It's odd, too, that when he finally produces one, it's a specific response to the playing of Kathryn Stott, who isn't closely involved with new music. Her territory is late-Romantic, and above all, Faure. But she's also versatile and resourceful, with a tough streak in her lyricism and an appetite for lots of notes - which Davies gives her in abundance here. The solo part of the concerto is dense with business, spinning endless skeins of scalic figures that it wouldn't be too fanciful to hear as Faure-esque. And without doubt this is a piece that places itself in the Romantic tradition, not so much for what it delivers - there are no billowing tunes or epic gestures - but for what it implies.

One of the idees lumineuses in the Goehr book suggests that "modernity" in music is determined by omission rather than inclusion: by what the composer leaves out (structure, form, harmonic givens) as opposed to what he leaves in. I'd like to hear Goehr argue that one through at High Table, and I'm not sure how far he could take it. But it's true - in a way - of this concerto, which strikes me as a game of glimpse-but-never-get. You sense some offstage drama playing behind half-closed doors and shuttered windows. Fragments of perhaps Prokofiev or Bartk filter through; the ghost of a waltz (Davies is fond of triple rhythms that don't quite register as such); the Brittenesque revenance of a climactic ostinato figure in the timpani ... It's like an attempt to define what a piano concerto might be in the late 20th century by reference to what it might have been, but ultimately isn't.

As with so many Davies scores, it also suggests a tension between two kinds of musical stance which, I think, relates to yet another observation in Finding the Key. One of Goehr's essays describes the 1950s as a time when the British avant-garde was in transit between theory and practice. In a post-war world starved of resources, new music had been limited to the condition of pencil-drawing: complex but unphysical, without immediacy. As resources and performing opportunities increased it was, says Goehr, like an awakening into oil-paint. Music found a new dimension. And to my ear, many Maxwell Davies scores still act out the transitional experience of that drawing-into-oils duality. The new concerto works through pages of comparatively academic two-dimensionality, then blossoms into sudden dynamism, colour, and unexpected gestural extravagance.

This is absorbing music, certain to repay repeated hearing, worth a place in repertory. And it's already gone into the studio for release next year by Collins Classics. What I'd like, though, is to hear it played not by the RPO under Davies, but by the BBCSO under someone else. Composers aren't always their own best friends with a baton, and I think this concerto would gain a lot from outside input. Not to say a decent stick technique.

In the well-established tradition of accompanists who turn impresario, the pianist Roger Vignoles has been running a song-recital series at the South Bank, based around Schubert and called Landscape into Song. Given the centrality of nature as subject and symbol to the 19th-century German Lied, it can't have been hard to find material for the programmes. And the result has been an exhaustive journey through moonlight on tree-tops, babbling brooks and lonely meadows, matching these exterior landscapes to the inner contours of the poet's soul.

No current singer makes the match with more finesse or literary sensitivity than the German baritone Matthias Goerne who, at 30, is one of the hottest properties on the Lieder circuit, recently signed up by Decca. Goerne gave two recitals in the Landscape series ( one of them unscheduled, substituting for Andreas Schmidt), and hearing the first of them I thought it lacked the ultimate intensity of, say, Wolfgang Holzmair with similar material. Goerne's "Erlkonig", for example, came with relish and drama, but like someone spinning a yarn: without the deadly chill that makes the final couplets. And, as always, I found him uncomfortable to watch. His small, repeating repertoire of gestures makes me think of Rowan Atkinson. To be the Mr Bean of Lieder isn't promising in Schubert.

But the voice - well, that's another matter. It's superb, alive, more fluent than his closest rivals, able to reduce the volume to a whisper with no sacrifice in tone. He phrases well, with perfect diction. I could listen to him all night long.

The Dutch bass Robert Holl, who gave an exemplary Winterreise with Vignoles at the QEH last Sunday, has a similar ability to sustain tone through diminished volume. But stylistically he's very different, with a bear- like strength he consciously controls into the most refined and clean of bass deliveries. Feet apart and staring downwards to the floor, he barely moves except to hold a song between his thumb and forefinger: a speck of precious dust held out toward the audience. In partnership with Vignoles's handsome playing, it touched something close to nobility in Winterreise's awesome progress to a fate beyond and worse than death.

The rest of my week looked to the promise of youth, starting with the London International Piano Quintet, making its home-town debut in a new series of Sunday-morning concerts at the Wallace Collection. Drawn from distinguished players, it has yet to find the the sense of five players rhythmically and intonationally ad idem. But this programme of Schubert, Mahler-Schnittke and Faure had its moments. And the Wallace Collection series is obviously fulfilling someone's Sunday-morning needs, because it's selling out.

The other youth event was a Guildhall School production of Haydn's La Fedelta Premiata, delightfully staged by Jamie Hayes as a Victorian country- house party with BBC2 classic serial characters. Will Bowen's carboard cut-out designs were a joy. Clive Timms conducted his own English translation with loving care. And the cast was notable for the crisp baritone of Mark Stone, the glistening mezzo of Victoria Simmons, and an enchanting soubrette, Natalie Christie, with a nice line in cute confusion. More fun all round than the Royal Opera's Merry Widow.