Classical; Ian Pace Plays Michael Finnissy; Conway Hall, London

There's a subtle ranking to composers' anniversaries: centenaries are formal and for the great and the good; celebrations at 40 seem premature. The birthdays that count for merit and assessment are 70 and 50 - the current half-century of Michael Finnissy being the occasion for a cycle of his complete piano music that began last Friday at the Conway Hall.

Finnissy's keyboard pieces (he is himself a notable player) remain an undiscovered country, which Ian Pace's six-part series should reveal to be a land of considerable extent: forthcoming concerts chart Finnissy the jazzman, the virtuoso, the folklorist and the transcriber.Tackling this difficult corpus requires a will of iron, and Pace has clearly mastered it note for note, which is no mean achievement in music of such unparalleled complexity.

Well, that's how the pundits describe it, and with good cause on the evidence of Friday's torrential outburst of rhythmic and harmonic frenzy. Yet this first helping was billed as "Finnissy the Romantic"; light years from Chopin, of course, but still a composer who in What the meadow-flowers tell me quotes Mahler, elsewhere sets the tune of Burns's most famous love lyric, and in Snowdrift and Autumnall created eminently plausible tone-poems in the genre that Tovey defined as "illustrative music".

Together with Sometimes I, a musical valentine, How dear to me and the aptly named Nine Romantics, these pieces made a substantial first half that set the parameters of the style: eclectic in its attitude to discourse, yet strangely uniform in the actual sounds produced. Though complex, its complexity is not the stuff of younger members of the difficult school. Rather, its effect is of teeming invention piled up without let or hindrance. "It's red hot," a colleague remarked at the interval. But can an artist be always so violently angry?

The second half gave us a chance to hear Finnissy working in a larger form - for that, in fact, was the impression of his epic Verdi transcriptions, 15 essays composed between 1972 and 1988, but running without pause as an arch of music. Pace played with authority, technically masterful and placing each gesture carefully within its wider context. Transcription was loosely defined: as the pianist, sustaining pedal down, probed extremes of sound throughout the keyboard's register, an occasional snatch of tune was like glimpsing an old friend.

What gripped was the phased control of tension and recession in a generous time-span. A gifted theatrical composer, Finnissy handled this aspect of his medium with consummate dramatic skill. The devil lay in the detail, a musical foreground that too often seemed a splurge of uncensored pitches. As part of a profligate style, such excess may be past redemption. Yet even at 50, it's never too late to learn a bit of self-control.