It's 250 years since the death of Johann Sebastian Bach, a fact which has been celebrated far and wide, in concert and on disc, in this special anniversary year. It's hard to say who might best be regarded as a living figure akin to Bach. He or she would probably not be too widely known, would be writing mathematically intricate music that, at its most complex, would create technical demands extreme enough to challenge performers for the next couple of centuries at least. If this all sounds a bit unlikely, then that may be because Bach is in some senses the most unlikely of great composers. And, at a time when accessibility is such a catchword, when dumbing-down is not so much a threat as an everyday occurrence, our willingness to celebrate the nature of Bach's achievement and his very special place in the heritage of Western music has a particularly important symbolic value.

Perhaps it was the fact that I had to miss the opening concerts of Sligo Baroque Music Festival's Bach programme that prompted these thoughts. This ensured that the work which greeted me in Sligo was the Goldberg Variations, in a performance of compelling focus by Malcolm Proud. Proud is not one of those harpsichordists who feels the need to draw attention to himself or any individuality in his approach to the music. The net effect is to cast him in the role of servant. But to be a servant faithfully carrying out the master's bidding in a work as demanding in its complexity and rewards as the Goldberg Variations is no mean achievement.

The festival's closing concert also offered a programme of music for a single instrument. Elizabeth Wallfisch introduced and played the Solo Violin Sonatas in A minor and C major, and the Partita in E, leavening the evening somewhat with a folksy-sounding solo, Senti lo mare, by Tartini.

Her spoken introductions had an agreeable, stream-of-consciousness feel to them, and were often humorous. The ideas communicated in her playing were clear, even when the execution was flawed. And there was a sense of exploration and adventure, too. Proud's Bach, one felt, was born of distilled experience; Wallfisch's seems to be still in the process of formation.

There were two other programmes which presented sonatas by Bach. But the two teams involved, Eleanor Dawson (flute) with Katherine May (harpsichord), and Darragh Morgan (violin) with David Adams (harpsichord), managed only a very limited success. A problem common to both recitals was an inconsistency of line from both flute and violin, creating an effect not unlike swallowed vowels, or fading in the reception of a radio broadcast. It's a phenomenon which stems from a flawed attempt at fashionably sharp dynamic shaping and, while only a minor distraction in the flute sonatas (where the major drawback was the unconvincing continuo playing of Katherine May), in the violin sonatas it made for an extremely unpleasant cocktail when combined with Darragh Morgan's consistently pinched tone, and variable intonation.

The Sligo festival has always prided itself on its marriage of professional and amateur elements. The latter was represented this year in a performance of Bach's motet, Jesu, meine Freude, by a choir trained over the weekend by tenor John Elwes, who conducted a performance in which the verses of the motet were interspersed with arias from three cantatas (sung by himself) and the Toccata in E minor, played by Malcolm Proud.

I'm sure the value of the enterprise for the participants was high. But as a concert-offering it was very patchy, rarely living up to the vitality and potential that was manifest in the chorales; and Elwes himself indulged in elements of an unusually barking style in his solos.

There were greater rewards to be had in two of the late-night programmes, a varied programme of Weiss, Lauffensteiner and Bach, by the gifted if still very flighty young lutenist, Richard Sweeney, and an even more varied programme of cantatas and trio sonatas by Bach, Handel and Telemann, given by the ensemble Passacaglia with soprano Helen Groves. Passacaglia's line-up, recorders with gamba and harpsichord, is nowadays an unusual one. The playing was stylish and alert and, with beautiful tone, Ms Groves gauged to perfection the scale of her contributions in the performing space of the newly-refurbished Model Arts and Niland Gallery.