How Messiah has become as much an institution at Christmas time as Santa Claus himself hardly needs explaining. All those rousing melodies – from “For unto a child is born” to the “Hallelujah” Chorus – have made it enduringly so, even though most of the oratorio’s content relates not to the birth of Christ but his death and resurrection. Handel actually intended it to be performed during Lent.

Big choirs numbering in the hundreds are synonymous with Messiah, and this time around the Sydney Opera House no doubt earned the prize for the sheer size of its performance under conductor Brett Weymark: 700 singers were assembled. By contrast, the ASO elected to go down the slimmed-down, authenticity path with forces comprising just under 40 choristers and 25 players. With Erin Helyard of Pinchgut Opera fame at the helm and an ace team of solo singers, we looked to have the more historically appropriate – and better – option in Adelaide.

People might remember that Helyard conducted Barrie Kosky’s eye-popping Saul at the 2017 Adelaide Festival, doing so with some flamboyance from the keyboard. So here he was again, standing at the harpsichord and sculpting Messiah with vividly sharp hand gestures and decorating its recitatives with panache. Meanwhile, Pilgrim Church’s gorgeous little chamber organ was brought in for additional colour – and Peter Kelsall played it expertly.

What a lovely sound they all produced. The Town Hall’s mighty JW Walker & Sons organ, thus rendered silent, could only look down with envy. Somehow Helyard had managed, in the usual tight rehearsal time, to transform the ASO into a very credible early music band by eliminating excessive vibrato, getting them to play with air, and swelling tastefully on only those notes that mattered.

Hallelujah to their effort: this was a thoroughly inspiring performance of true Handelian splendor. Helyard refrained from rushing tempos, as can easily happen in over-enthusiastic “early music” performances. Setting the overall tone, the opening Sinfonia possessed wonderful gravity as well as elegance, and the pacing of each aria and chorus felt exactly right.

As with Handel’s other great oratorios, Messiah is so close to being an opera that dramatic pacing is absolutely called for. One could admire this, for instance, in “For unto us a child is born”, where the choir began with a whisper but resounded with full force at the words “Wonderful, Counsellor… The Prince of Peace”. These choruses are so big and generous (like Handel himself), but here was a lesson in less is more: big and flabby just won’t do if this work is to really shine.

We certainly got lucky with the soloists. Specialist Handel singers are obviously in hot demand at this time of the year, and fortunately the ASO procured a quartet that really could not have been bettered. Comprising soprano Sara Macliver, counter-tenor Russel Harcourt, tenor Michael Petruccelli (replacing Nicholas Jones, who was in the Sydney performance) and bass David Greco, they put in superlative individual performances and congealed well as a team.

A word about Harcourt first. His light, angelic voice in the arias “But who may abide” and “He was despised” cast a spell such as the Town Hall has rarely witnessed (at least in my experiences there). There are more male singers excelling in alto and castrato roles in Baroque music these days (it requires a special technique), but this Sydney singer is extraordinary. Unimaginably clear and gentle, his voice is devoid of any of the lower tell-tale resonance that characterises a male singer. He was so very poised, too, turning graciously to face his fellow singers when it was their turn. What a nice touch.

Greco was extremely impressive in the bass arias “The people that walked in darkness” and “Why do the nations”. He is able to crack the air with thunderous impact in a voice that almost speaks: he enunciates words with enormous expressive impact.

Macliver is quite simply the best Australian soprano for Handel. She always delivers top-notch performances and was sublime in “How beautiful are the feet”. Making up the quartet, Petruccelli was every bit their equal in his noble rendition of “Comfort ye” and “Ev’ry valley”. All singers understood Handel the same way.

But the choruses are where the mighty stuff happens. Rising to their feet with precision, Adelaide Chamber Singers were magnificent in “And the glory of the Lord”, right through to the concluding “Amen”. Christie Anderson, as ACS’s new director, can take full credit for all their wonderfully disciplined singing.

Predictably, virtually all the audience members rose to their feet in the “Hallelujah” Chorus – a quaint, persistent tradition that reputedly goes back to the time of King George II.

Again, though, it was the orchestra who earned particular admiration for venturing well outside its usual zone and taking on elements of Baroque performance practice so effectively. As always, it is a compromise when modern instruments are involved, but on this occasion it was a happy one. Helyard clearly does magic with them.

All the ASO players did well, but to single out just one for special praise, Andrew Penrose on timpani was absolutely terrific: his courageous strikes in the oratorio’s grand ending sent everybody out on a high.

Messiah was performed at the Adelaide Town Hall on December 16.