The celebratory, cerebral and contradictory elements inherent in this diverse programme of Haydn, Mozart, Poulenc and Stravinsky didn’t quite disguise some uneven performances in Thomas Søndergård’s third prom concert.

It was problems of balance that marred an otherwise exciting rendition of Poulenc’s Concerto in G minor for Organ, Strings and Timpani. The strings of the BBC National Orchestra of Wales sounded as if they were relishing this work – but its contradictory fairground vulgarity and Bachian majesty would have been better illuminated if dynamic contrasts had not been quite so severe and if the clean string lines (superbly rhythmic) and menacing timpani had not been occasionally overwhelmed by the “Father Willis” organ from an otherwise flawless James O’Donnell. (It was another British organist – Francis Jackson – who gave the first Proms performance in 1957, and Anne Maddocks, who gave the British première in Chichester Cathedral in 1943.) The work’s opening bars were magnificent, as too were the perfumed harmonies of the concluding section with its poignant solo viola and cello (Carl Hill and Rebecca Gilliver) and which beautifully underlined the composer’s observation that this “is not the amusing Poulenc but rather Poulenc on his way to the cloister”.

Like this concerto, the stimulus behind Stravinsky’s Symphony of Psalms was the result of both a commission and a re-awakening of religious faith, albeit expressed in a strikingly different way and with Bach as a connecting thread. Stravinsky’s innovative scoring was emphasised by the physical space that separated brass, wind (without clarinets) and lower strings, with two pianos positioned in the area normally occupied by violins and violas. A brisk tempo and that much-celebrated opening chord set in motion Psalm 38, its solemnities neatly delivered by the BBC National Chorus of Wales, whose pure soprano tone gradually gained conviction and weight for the austerely exultant climax. The counterpoint in the central Psalm was carefully shaped, even if the longed-for salvation from the chorus required more conviction. More persuasive was the other-worldly objectivity and rapt austerity of Psalm 150. Here, choral discipline and intonation were never in doubt and, even if the singing was a tad clinical in places and diction could have been crisper, this performance more than suggested music of the spheres.

After the interval Søndergård gave an uplifting account of Haydn’s Te Deum in C major (Hob. XX11c: 2): its festive qualities highlighted by the six brass players (three with natural trumpets) who stood throughout the work’s ten minute span, and a re-positioned chorus who sang in a mixed-voice format. Everything worked well here, with orchestral forces complementing and balancing a now full-throated and well-projected choral sound that was notably effective in the repeated pleas of “non confundar in aeternum” (never let me be confounded).

The vigour Søndergård drew from the Haydn took a while to transfer to Mozart’s Symphony no. 41 in C major, K.551 “Jupiter”; its performance marked by strict observation of repeats and with no use of vibrato. Despite scrupulous preparation, the opening Allegro felt limp and drama never quite found its way into the development. Eloquent woodwind contributions enlivened the Andante but the overly long Menuetto seemed polite. The Finale, however, was a zesty affair, brimming with energy and if the brass were occasionally over zealous Søndergård’s invigorating tempo brought new life to this much-performed work.