As orchestras go, Le Cercle d’Harmonie is relatively young, founded just eleven years ago in order to revive older performance styles on period instruments, and youth is well represented in its ranks with players from differing nationalities. Its Proms debut was not without incident: one of its regular violinists managed to get herself entangled in the rigid UK visa bureaucracy (details were given in her cri de coeur online) and had to withdraw.

On the basis of this appearance, it is not difficult to see what its spiritus rector, Jérémie Rhorer, views as its defining characteristic. Harmony, plain and simple. All well and good, one might suppose, since textures were consistently well blended. However, winds rarely spoke winningly (as they so often can), the timpani were kept well in check and strings had little bite. For a period ensemble this is tantamount to the kiss of death: smoothing out the edges and concealing the warp and weft don’t really work.

There was nothing in the opening work, Mozart’s grand symphonic statement in E flat, to suggest that this was one of the last great things he ever wrote. Smudging the string lines in the opening statement was already inauspicious, with a tempo that was well ahead of the marking in the score, and although Rhorer had all the violins grouped on his left (the six violas immediately to his right), they sounded underpowered. This was a particular problem in the second movement, where the minor mode became but a distant sighting in the musical undergrowth. Music-box Mozart might suit some, but this was overplaying Apollonian grace to the detriment of Dionysian inspiration. Matters didn’t really improve in the Minuet (which is not supposed to sound like a jig), with the Trio section under-characterised. When the abiding impression of the very brisk finale was that of a sewing-machine whirring along, you couldn’t help feeling that this was a conductor merely going through the motions.

The concert was bookended by another symphony, this time anchored solidly in the Romantic tradition. Germans have a reputation for being perfectionists and Mendelssohn was no exception. In 1842 he observed to a musician friend: “In everything I have written down there is at least as much deleted as there is allowed to stand.” He was plagued with considerable self-doubt about his “Italian” Symphony, to which he made constant revisions, so much so that it was not given its first performance in Germany until after his death. Although this performance by Le Cercle was much better played than the K543 with which the concert started, I cannot help feeling that if the composer himself had been in the audience he would have wanted to go back to the drawing-board.

To be sure, there was plenty of energy coming from Rhorer in the opening movement, but a singing upper line – so essential if the sense of exultation is to be adequately conveyed – was hardly in evidence. The many carefully crafted string figurations were largely left to look after themselves, with cellos and basses often no more than a rumble, though the mellifluous sound the wind produced (the clarinets especially) was some compensation. At least in the second movement Rhorer resisted the temptation to hurry the music along. It is after all the recreation of a religious procession, and the Andante marking and the all-important dynamic shadings were properly respected. Sadly, in the third movement flabby playing exposed a recurring weakness in Rhorer’s approach throughout: an absence of sprung rhythms. An over-ambitious tempo for the finale which blurred all articulation (the flutes cruelly challenged) was a miscalculation.

Indeed, without the lustrous tones of the young Italian soprano Rosa Feola, one of Renata Scotto’s protégées, this concert would have remained decidedly insipid. She appeared either side of the interval in two concert arias. These now seem like a relic from the past. How many contemporary composers bother to write such short pieces for the human voice these days? Indeed, Mendelssohn’s Infelice was last given at the Proms in 1936 (by the great Slobodskaya), and one wonders why. Unfaithful lovers are a recurring theme in human experience and have repeatedly found compelling musical expression. Infelice was an ideal vehicle for Feola’s gleaming voice, her creamy tone supported by seamless transitions through the registers (the composer requiring a wide tessitura as well as an impressive dynamic range), and she beautifully communicated the range of heartfelt emotion at its core. Ah, lo previdi, loosely based on the story of Andromeda, was one of Mozart’s many concert arias. Here, Feola’s instinctive command of style (she is currently singing Susanna at Glyndebourne) enabled her to negotiate minor miracles of phrasing without disrupting the sense of line. We will undoubtedly hear more of her.