Being the Chief Conductor of the BBC Symphony Orchestra, Sakari Oramo already has a full Proms schedule, conducting four of their concerts including the last night. But Oramo was a star violinist prior to being a conductor, and likes to keep his hand in, so for today’s lunchtime Chamber Music Prom at Cadogan, he joined Janine Jansen – herself a regular visitor to the Proms, with two other appearances this season – for a performance of Prokofiev’s Sonata in C major for two violins, Op.56.

The pair may have looked an oddly matched couple, Jansen resplendent in flaming black and orange evening gown and somewhat taller than a rather dapper looking Oramo. And their facial expressions may have been very different when playing the most intense moments: flashing eyes and swaying body from Jansen, a shivering jowl from Oramo. But from the sound that emerged, there could be no doubt that here were two musicians who enjoyed playing together.

Which is just as well, since the Prokofiev sonata looks fiendishly tricky to bring off. The work has been described, we were told, as being like “eavesdropping on a conversation between friends”: that may be so, but if it is, the conversation is a very erratic one, with the friends frequently wandering off in their own directions before coming back together into a blend. The violin lines interweave sinuously, requiring the soloists to shift through endless serious gear changes while remaining perfectly sensitive to each other, not just in timing but in mood.

Jansen and Oramo achieved this impressively, and one could only admire the excellence of timbre in widely different moods: delicate tracery in the first movement, heavily accented dance rhythms at the start of the second, long, hauntingly evanescent con sordino passages in the third, mischievous fun in the end. This is Profokiev at his mercurial best, and it was clear that the two soloists were enjoying every moment.

The double violin sonata was framed by two works for solo violin and piano, played by Jansen and pianist Itamar Golan: first Prokofiev’s Five melodies for violin and piano, Op. 35b and, to close the programme, Schubert’s Fantasie in C major for violin and piano, D934.

Given that Golan is a regular collaborator of Jansen’s, I expected their playing to be well balanced and coordinated with each other, so I was disappointed that things didn’t seem to turn out that way. Rather, I felt like I was listening to a pair of great individual soloists but not to a great blend. Partly, this was a simple matter of volume: much of the time, Golan was far too much louder than Jansen, this being particularly noticeable in any extended pizzicato passages, in which the violin was almost inaudible between washes of rippling piano notes. (As ever, with problems of balance, this may have been different in different seats – the balance on the iPlayer broadcast is better). But there were also timing issues. Golan wasn’t always perfectly smooth in those rippling runs, and he often played with a fair level of rubato. If I listened just to the piano, Golan’s playing was thoroughly enjoyable, but I never felt total confidence that Jansen’s violin was quite in sync with him.

There was a great deal to enjoy in Jansen’s playing. The first Prokofiev work is a 1925 arrangement of a set of five vocalised melodies for soprano written some five years earlier, and it gives plenty of opportunity for the violin to show off its lyrical qualities. Jansen produced exceptionally pure tone in the delicate second melody, featherlight touch in the fourth and a delectable series of harmonics in the fifth, said by Prokofiev to have represented the shimmering Pacific Ocean (the original vocal work was written in California).

The Schubert starts with the gentlest of slow note crescendi on the violin, played exquisitely by Jansen, who seemed transported to a different plane. The next movement becomes very classical, showing Golan at his most elegant and delicate, moving on to something quite fiery. There follows a series of variations on the theme of Schubert’s song “Sei mir gegrüßt”, which gives the performers a chance to explore a variety of different textures on the same harmonic and melodic base. Togetherness of the performance improved through these sections, bringing the concert to a satisfying close. Oramo then rejoined the other two musicians for an encore of a deliciously sentimental pair of numbers incorporating some distinctly schmaltzy waltz tunes which turned out, improbably, to be two out of a set of five violin pieces by Shostakovich. It was a chance for all three musicians to let their hair down and send us off with a smile.