The transfer of the International Piano Series to St John's Smith Square while the Southbank Centre undergoes a facelift is proving successful and popular. An elegant venue with a fine acoustic and a beautiful Steinway piano, coupled with one of the UK's most gifted pianists active today made for an evening of music making of the highest calibre, in a diverse programme which opened with Schubert and closed with Rachmaninov.

Schubert's second set of Impromptus D935 are less frequently performed than the first set, with the exception of the third of the set (a set of variations based on the Rosamunde theme). The first and the last, both in F minor but very contrasting, were presented in this concert. The word "Impromptu" is misleading, suggesting a small-scale extemporaneous salon piece or album leaf. Schubert's Impromptus, composed in 1827, his post-Winterreise year of fervent creativity, are tightly-structured and highly cohesive works. 

There is nothing "small scale" about the opening of the first of the D935, and Steven Osborne's account of this was brisk, almost terse, and bold, with a grandeur redolent of Beethoven at his most expansively gestural. But Schubert does not linger in this territory for long and soon the music moved into a far more introverted realm. The middle section, tender duetting fragments over an undulating accompaniment, was poetic, intimate and ethereal. By contrast, the other F minor Impromptu was infused with Hungarian flavours, with offbeat rhythms and twisting scalic figures. Osborne pulled it off with a modest bravado, alert always to Schubert's miraculous harmonic shifts and fleeting moods.

The thrumming, dancing rhythms of Schubert were reflected in Debussy's Masques, while the second set of Images was suffused with colour, vividly portrayed with fine attention to contrasting narrative lines and interior details of each piece. Here, Osborne recalled Schubert's intimacy in his sensitive handling of this atmospheric music: bells chimed distantly, the moon peeped shyly, iridescent fish darted in a limpid pool. L'Isle joyeuse brought the first half to a close with a lithe, playful virtuosity and a palpable sense of enchantment.

George Crumb's Processional, not listed in the original programme for the concert, was an unexpected revelation. Composed in 1983 for Gilbert Kalish, it is a study in colour, both harmonic and pianistic, and is largely built on a motif of pulsing double cluster chords against which little fragments of melody appear in the high and low registers. As the piece proceeds, a hypnotic 'resonance effect' is created, and Osborne's expert control and intonation revealed unexpected colours and shadings in the work, reminiscent of Debussy's kaleidoscopic soundworld. 

More images were evoked in Rachmaninov's Études-Tableaux, as Osborne performed selections from both the Opus 33 and 39 sets. The composer suggested the performer might "paint for themselves what it most suggests" in the music and each Étude has a distinct character, terse yet expansive in texture and mood. Opus 33 was written when Rachmaninov was engaged in large-scale pieces, including the Second Symphony and Third Piano Concerto, and these miniatures seem to express in microcosm the grand ideas of his larger works. The Opus 39 set was the last music Rachmaninov wrote before he left Russia in 1917 and many of the works in this opus seem more cosmopolitan in character. In both sets, however, there is an underlying sense of the composer's heritage and culture in the use of harmonies and rhythms drawn from folk music (the haunting flickering open fifths of Opus 33, no. 2, for example). 

These are technically demanding pieces: as "etudes" or studies they are designed to test the pianist's capabilities as well as creating colourful and expressive narratives. Osborne can do muscular and emphatic playing in spades, yet what was more striking here, as elsewhere in the programme, was his sensitivity to subtle details and nuances, his control and modesty, which brought an unexpected intimacy to the pieces.