Wolfgang Amadeus Mozart’s Requiem is one the most performed of his works, famously unfinished at the time of his death, but completed at the demand of his widow (money was, as ever, in desperately short supply) by his pupil Franz Xaver Süβmayr. For most listeners that is the end of the matter, but anyone even slightly curious about this completion is soon aware of some dissatisfaction on the part of musicians and musicologists with Süβmayr’s work. It’s not just that it’s not Mozart; it’s the suspicion that a better musician could do it better. Indeed, the first efforts by Josef Eybler were better, but for unknown reasons he never completed the job. So it is that various musicologists have sought to improve or improve on Süβmayr.

I am not qualified to judge its scholarly merits and how Dr Benjamin-Gunnar Cohrs’ decisions compare with those of others who have worked with this material, but I can report that in performance this new version of the Requiem had a vitality and cogency that is not often consistently apparent in performances of the Süβmayr version we are used to hearing. Fugues end each section of the Mass and Cohrs’ reworking of the “Amen” fugue and the “Hosanna” fugue give the Mass a formal coherence that Süβmayr’s weaker continuations fail to achieve, and Cohrs’ new continuation of the Agnus Dei brings the work to what is ultimately an energetic and triumphant close. The final cadence, a very spare chord known as an “open fifth” in the usually heard version, is here replaced by the full major triad, so that the bereaved are not left without hope, which Cohrs surmises would have been Mozart’s likely intention, and is justified by similar examples in other Mozart manuscripts where the full chord is similarly signified. This new version remains based on the conjecture that Mozart had communicated the opening thematic material of the missing sections to Süβmayr, and concerns itself with the orchestration throughout and the continuations of the unfinished or absent sections.

The four soloists were all excellent and made a beautifully balanced quartet at this performance in the St Marienkirche, Dortmund. Soprano Karolina Brachman had a warm clarity that was never shrill, and alto Dorothe Ingenfeld’s rich tone was a delight each time it rose up through the ensemble. Jan Hübner, tenor (and chorus master of the excellent Alsfelder Vokal-Ensemble), was expressive, precise, but unforced, and George Stevens’ bass voice was magnificently articulated, stirring but never vulgar in the Tuba Mirum. He responded well to the famous trombone solo which in Cohrs’ version is no virile outburst, but a moderated, more subtly expressive dramatic gesture.

The performance made a thoroughly convincing case for this new edition of the score. It is a reworking that deserves to be heard, and it may just be that the Süβmayr to which we have become accustomed might find its position in the repertoire a little less secure.

The whole concert, which played without an interval and was not interrupted by applause before the end, had been carefully planned so that Mozart’s last work had a context worthy of the gravity of its content – it was not just a second-half concert piece. The greatest surprise was delivered by the two rarely heard works by Haydn, Salve Regina and Libera me, both of them magnificent. Noticeable here, and throughout, was the wonderful way in which the conductor let the choir and orchestra respond each to the other in the expressive moulding of the phrases. The Requiem Gradual by Cherubini was immediately appealing, though perhaps with a touch of sentimentality that Mozart always avoids. The two chants from the Roman Gradual, the first an unaccompanied tenor solo, confidently sung by Hübner, the second for women’s voices alone, evoked the ancient religious tradition to which all the works belonged. The preparatory pieces were brought to a touching close with a finely nuanced performance of Mozart’s Ave verum corpus.

The Alsfelder Vokal-Ensemble suffered from the acoustic, their voices, though always audible, failed to ring out above the Göttinger Barock-Orchester. But their singing was of high quality, and both choir and orchestra performed with expressive warmth, not seeming hidebound by scholastic pedantry as has sometimes been the case with period-instrument performances. And Dr Cohrs, whom I have only known before as a Bruckner scholar, revealed himself to be a communicative conductor, able to provide flowing gestures and cues, and elicit a performance that was as committed, moving and revealing as one could wish for – nothing of the inhibited scholarly time-beater here. Come the finish, the concert was greeted by standing ovation.