At the end of July Andris Nelsons makes his debut in Bayreuth, opening this year’s Festival at the shrine of Wagnerdom with performances of Lohengrin.

And last Saturday, in one of the most ambitious enterprises ever mounted by the CBSO, he conducted a huge assemblage of forces in a concert-performance of this drama which mixes mysticism with historical realism in inimitable Wagnerian manner.

Far from being a dummy-run for next month, however, this account set a standard which Bayreuth forces will have to work very hard to emulate. Fortunately, with Nelsons at the helm, provided it’s not a questionable production, they’ll probably bring it off.

What Bayreuth doesn’t have is the co-operation of one of the finest auditoria in the world. Symphony Hall played its part so brilliantly on Saturday, accommodating a vast panoply of extra brass ranged aloft in front of the organ, what was virtually a second orchestra offstage, as well as permitting offstage singing (such as Lohengrin’s first entry) to come through loud, clear and unforced. There were also expert, easily legible surtitles (this important adjunct has improved so much since it was first invented, and the only bloomer I saw here was the misspelling “hansome”).

Onstage was the vast orchestra, the equally vast CBSO Chorus, swelled by men from the London Symphony Chorus (a tremendous amount of work for male choristers in this piece), London Voices (in tiny individual roles), and the superb CBSO Youth Chorus, joining in this auspicious occasion with enthusiasm and disciplined commitment.

Rehearsals had been many and intensive, and the supple phrasing, bold articulation and depth of tone from the orchestra was even more apparent than when we hear these amazing players after normal rehearsal conditions. Choral projection was as forward and vivid, even in the most quietly articulated passages, as we have come to expect under Simon Halsey’s tutelage.

Lance Ryan’s Lohengrin was a little steely of tone, but totally engaging, not least in his great Act III revelations, Hillevi Martinpelto made much of the somewhat wan character of Elsa, Gidon Saks was a commanding, sympathetic King Henry, Eike Wilm Schulte an incisive Telramund, and Kostas Smoriginas rounded out the two-dimensional role of the Herald to engrossing effect.

But outstanding in this well-complemented team was mezzo-soprano Lioba Braun, her Ortrud a gripping model of evil conveyed by feminine wiles, the strength of her singing in no danger of suffering in this accommodating acoustic.

But where was Nelsons in all this? Amazingly, I scarcely noticed his physical presence, so absorbed was I by his shaping of the structure (three lengthy acts seemed to fly by), his elegant balancing of textures and sonorities, and the sheer selflessness of his musicianship, putting all his gifts at the services of the performers in order to convey every last detail of the composer’s intentions.

Rating: 5/5