Brautigam plays Beethoven on Graf at BRQ Vantaa Festival

Upon entering the gracefully proportioned surroundings of Vantaa's St Lawrence Church, you realise that although this is a concert of Romantic piano music, it's not going to be the usual big, rich sound of a Steinway or Yamaha grand: on the small stage in the position of the altar is a beautiful creation in richly grained wood. It's a replica of a piano made by Conrad Graf (1758-1851), who made around 3,000 pianos, one of which was Beethoven's last piano.

It's not going to be a fussy gig, either: Ronald Brautigam, a mop of unruly grey hair over bright eyes and a genial smile, is obviously relaxed, gives a quick bow and gets straight to the rather smaller-than-usual keyboard. He is playing from the score and turning his own pages, and as he launches into Beethoven's late Piano Sonata no. 30 in E major, Op.109, we get to appreciate that both Brautigam's technique and the sound are quite different from those of a standard modern performance.

Brautigam's technique is one of simplicity and efficiency. For the whole concert, his hands hardly move vertically, moving along a horizontal line just above the keys as if it were a railway track. There are no sweeping gestures, and all the work of articulation is done with fingers – except for a few occasions where he wishes to emphasise one of the lowest notes. The result is an unparalleled legato on the rippling runs that pervade all of the works this evening: you hear each note, but you also hear them fuse into a phrase with perfect evenness and shape.

That clarity comes at a cost: the dynamic range of the instrument is far lower than that of a modern grand. The fingerwork is used because you get your volume by speed of hitting the keys, not by hitting them with weight (with the exception of those lowest notes). It's not, of itself, a weighty sound and, as Brautigam explains, an instrument like that needs some help from the room. St Lawrence's Church provides exactly that kind of help: there are enough varied hard surfaces from gallery, organ pulpits to provide resonance and colour, without spilling over into the kind of long reverberation time that would kill the music.

The end of the first movement usually sounds violent: here, it sounded emphatic and authoritative, but in no way enraged. One's preconceptions of the personality of the aging Beethoven are challenged by realising how the music sounds on an instrument such as he might have played. The third movement cantabile sounds delicately beautiful, but with marked accenting in the underlying rhythm. Throughout, even in the most rapid-fire portions, he maintains perfect smoothness in the ebb and flow of the music, relaxing to the evanescent ending.

Brautigam opens the Mendelssohn Scottish Sonata with a big flourish, and immediately moves into the rippling trills – the perfect legato is even more impressive than it has been hitherto. Schumann's Kreisleriana is another ripple piece: I'm going to confess that it doesn't make the same emotional impact on me as the Beethoven, but I can't fault the quality of the playing, with Brautigam displaying the lightest of touches as the runs approach the highest notes of the keyboard, or providing fiery ripples in the bass where Schumann marks the music Sehr lebhaft (very lively). The "playful" last movement sparkles with humour, down to a big accent on the last, individual, low note. The concert ends with an encore of Für Elise, reminding one that there's is rather more to the "bagatelle" than its simple beginner's piece main theme.

BRQ Vantaa Festival is notionally a Baroque festival: this evening's concerts straddled the Baroque from either side – Brautigam was followed by a rather wonderful, meditative concert of medieval music – but gave a fine demonstration of the way in which looking at works with older eyes can shed new light on them.