If your ears happen to frequent the frequencies of the BBC’s classical music radio station, it’s highly possible that you’ll have been swamped by piano music this monsoon season. Piano notes have poured down upon us, flooding the airwaves with this extraordinary instrument’s capacity to evoke everything from orchestras to ocarinas, from tempestuousness to tranquillity, from Moonlight to Raindrops.

Despite such pianistic inundation, I was keen to catch the eighth and final of Paul Lewis’ Schubert Piano Cycle series in Bristol’s finest chamber music venue, the incomparable St George’s. Lewis’ epic journey through Schubert’s piano output was to finish on a high with the composer’s final three piano sonatas, nos. 19, 20 and 21: an exciting but not entirely unproblematic programme, which ran the risk (just like Radio 3’s “Piano Season”) of giving the audience too much of a good thing.

Schubert wrote his last three sonatas in the year that separated his death from that of the great heavyweight of Viennese composers, Beethoven. And indeed, the weight of the late composer seems heavy on the shoulders of Schubert in his Piano Sonata no.19 in C minor, what with its Beethovenian key centre and its Pathétique-like opening. Our pianist seemed to be equally weighed down, perhaps by the ghost of the composer whose handsome, stern-set, never-smiling bust Lewis – or his management – tries so hard to emulate. Indeed, one would usually associate the ferocious power with which he attacked the first movement with Beethoven rather than Schubert, which, given its/his Beethovian nature, shouldn’t, perhaps, have surprised. However, the movement isn’t just compositional emulation, and the more Schubertian moments – the simplistic melodic beauty of the second subject, for example – really suffered under Lewis’ tense heavy-handedness. Often, phrases which were crying out for moderation of tone and dynamic were hammered out forte; such rough treatment of Schubert’s serenity and St George’s magnificent acoustic was bewildering, especially for one who is stranger, after this series, to neither the composer nor the venue.

The second movement gained our ears some respite, Lewis’ tempestuousness transformed to temperateness. Any temptation for rubato was quashed, and the slow, measured movement was a lesson in precision and poise. Levity, though, is not a word one would associate with Paul Lewis, and this was illustrated by the seriousness with which he approached Schubert’s abrupt mid-phrase break-offs in the Minuetto. However, a lighter side did begin to emerge in the finale, with its repeated galloping rhythm, heavily scored in the mid-range, contrasting delightfully with tinkering triplets in the treble. This last movement was evidence of the wonders that dynamic and emotional variety can bring to an interpretation, and signalled what was so gravely lacking in the first.

As previously mentioned, the choice to programme three extended Schubert sonatas in one concert posed a problem of over-exposure, one in which the middle work (performed directly after the first and before the interval) runs the risk of being obscured by the other two. Alas, this turned out to be the case, and the Piano Sonata no. 20 in A major was the evening’s least memorable musical utterance. This is not to say the performance was not a good one; Lewis’ metaphorical tie-loosening (the literal top button on his tie-less black shirt remained firmly clasped) and increased warmth allowed a healthy dose of rubato to find its way into the deliciously beautiful Andantino, from which emanated the evening’s first truly moving music. This sonata, with its far less intensely dramatic music, matched with a far subtler, less belligerent interpretation than its preceding number, suffered from being squeezed into the programme. But if it served as a way to relax our pianist before the series’ Schwanengesang, the Piano Sonata no. 21 in B-flat major, then its inclusion is to be celebrated.

For after the interval, Paul Lewis seemed a man transformed. The tensed jaw, the shoulders were far more relaxed; the guttural grunting that had punctuated previous climactic moments were fewer and farther between; and Schubert’s serenely simplistic melodies; his harmonic caresses through unrelated keys; his delightful fragments of phrases that capitulate lazily to contented rumblings in the bass: all sang with an emotional musical engagement that made the first movement radiate with the warmth and gentleness it demands. The second movement’s quiet persistence rose to stateliness, the third’s delicacy was beady-eyed and shining, and the finale, after its striking, bell-like octave G, wove its way through minor keys to a breathtaking outburst of a coda, in which Lewis just about managed to hold his countenance as he rocketed to the end. The audience certainly didn’t hold theirs as they erupted into thunderous applause, ending a concert which confirmed my ambivalence to the piano, and its capabilities of provoking storminess fit to give you earache, and calmness to melt the stoniest of facades.