Neither of the BachFests that I’d attended previously at St. Alban’s Episcopal Church, in 2010 and 2011, suggested that program selections hewed religiously to a settled format or exclusively to works that emerged from the prolific Johann Sebastian and his family. Composers and instrumental mixes varied nicely within each of the two concerts, with a noticeably different look in successive years. Yet I still found myself surprised by how different BachFest X was from those I’d attended before. There were no violins or wind instruments to be seen throughout the 2015 concert, and aside from the Music @ St. Alban’s artistic director, cellist Barbara Blaker Krumdieck, no familiar faces. Nicolas Haigh played the only other instrument I’d seen at a previous BachFest – a harpsichord. The theorbo played – and punctiliously tuned – by Williams Simms was similar to the archlute that made a tantalizing appearance at the 2011 fest, but this Baroque instrument was more massive in size, more robust in sound, and more in the spotlight over the course of the afternoon.

All of these musicians took turns as featured soloists, and so did the vocalists who rounded out the ensemble – mezzo soprano Tamsin Simmill, and soprano Margaret Carpenter Haigh. The vocalists made the biggest difference for me between this BachFest and those I’d reported on before, not only dominating the selections performed by the full ensemble but also making them the most festive.

Kicking off the fest, Krumdieck led the group through the audience down the center aisle, and they all jumped into Barbara Strozzi‘s “Merci di voi” when they reached the chancel. Singing at the opposite end of the ensemble from the mezzo, Haigh had more of the ornamentation than Simmill and, when the vocal passages echoed or overlapped one another, it was usually Haigh who led the duo into them. The duet, from the composer’s first book of madrigals (1644), had a pleasing arc, starting at a loping andante pace, speeding up briefly before luxuriantly subsiding. Neither of the vocalists had any difficulties with the challenges of the work – an excellent harbinger, since there were six more pairs of quotation marks in the program booklet.

Simmill took on the first of these, Purcell’s “Music for a While,” after a beguiling intro from Simms on the theorbo. The choice suited the mezzo well with its veiled references to snakes, Alecto (one of the three avenging Furies in Greek mythology) and her whip. (This piece is part of Purcell’s incidental music for the adaptation of Oedipus Rex (1679) by John Dryden and Nathaniel Lee.) Performing with reading glasses and a minimum of gesture or facial expression, Simmill seemed altogether acclimated to the concert stage.

Notwithstanding her many concert, consort, and recording credits, Haight sang Purcell’s “If Music Be the Food of Love” as if she were a moonlighting opera diva, making no effort to suppress her acting urges. Even without any elaborate contextualizing from Shakespeare’s Twelfth Night, the situation and emotions soon came through vividly in Haight’s performance. Haight’s long, velvety vowels at the start of her song created a languid intimacy, and the quickening of her pace brought on a heightening of the excitement.

The contrast between Simmill’s and Haight’s styles was most interesting – and effective – when they took on key roles from Monteverdi’s L’Incoronazione di Poppea (1642), with Simmill as the Emperor Nero and Haight as his newly crowned Empress, the title character, in their climactic “Pur ti Miro” duet. This blissful duet drew the most attractive singing that I heard from Simmill all afternoon and the sweetest vocal harmonies, more like the concord you might expect in the boudoir some hours after Poppea’s coronation.

Sticking with Monteverdi, Haight performed a solo madrigal, “Si Dolce e’l Tormento” (1614) that acquired a duet-like flavor with a couple of prolonged interjections from the theorbo, lovingly played by Simms. There was a little more bite to Haigh’s Italian here – a clear signal that she was also having a good time. But the most rousing ensemble of the afternoon occurred when Simms switched to Baroque guitar for “Zefiro Torna,” a gem plucked from Monteverdi’s posthumous Ninth Book of Madrigals (1651). His strumming took on a percussive edge that swept the two vocalists into a fandango fever.

With Oedipus, Shakespeare, and an adulterous Emperor on hand, we could be tempted to forget we were in a church until the closing  ensemble, “Wir eilen mit schwachen” from Bach’s Cantata No. 78 (1724). Krumdieck had her best moments here as an accompanist, but the festivity clearly emanated from the vocalists, with delicious harmonies that were eclipsed only by the duet’s contrapuntal delights. Yet neither Bach nor Krumdieck was overlooked before we reached this giddy, worshipful finale.

Two formidable Bach solos came from the instrumentalists, beginning with a surprise from Haigh, who was listed on the program as a harpsichordist only. Instead of playing the “Sinfonia” from Bach’s Partita No. 2 (1726) on that instrument, he retired to the far wall where he sat down at the church organ. It’s not the mightiest I’ve heard, but Haigh was able to give the dense opening some real ferocity. Then in the more nimble midsection, Haigh chose a softer voicing from the St. Alban’s organ so that it stood apart in soothing mentholated relief. The conclusion was no less impressive when Haigh maintained the accelerated tempo while returning to the organ’s more robust timbre, for here there were some knotty fugal passages, and the organist controlled both hands (and strands) beautifully.

Krumdieck ventured boldly where so many of the world’s great cellists have left their imprint, giving us the four last movements of Bach’s Unaccompanied Cello Suite No. 1 (1717), which became more lovely with each movement, reaching its zenith in Menuet 1 and 2. Slightly quickening the pace of the Sarabande so that we arrived at a medium tempo, Krumdieck graced these movements with more control and admirable lightness – exactly the word that Rostropovich used to describe the entire suite. Simms could have wandered almost as extensively through works that Bach wrote for unaccompanied lute, but he chose more exotic terrain, playing a D Major Suite by Robert de Visée for theorbo (1716). Reaching the fourth of the six pieces that he played, Sarabande, the music began to transcend divertimento status and acquire some truly engaging lyricism. The “Chaconne des Harlequins” had even more zest while retaining some of the Sarabande’s quiet dignity. Simms smartly inserted the Chaconne before the Gigue instead of after. By doing so, Simms crafted a performance of the suite that ramped up continuously in liveliness and invention, ending merrily in 3/4 time.