This summer, Buffalo’s hottest musical export could well be the a cappella singing group Vocalis. The singers are bound for Britain, for a tour that peaks with a performance at the prestigious Cambridge Summer Music Festival.

As a kind of warm-up, the group is singing two Evensong services at St. Paul’s Cathedral in downtown Buffalo. The first is Wednesday, and the second is July 22. Both are at 7 p.m. and, because they are worship services, they are free.

They offer an excellent chance to catch the Vocalis singers at a watershed moment in their 12-year history. The Cambridge festival concert, while richly deserved, was the result of serendipity, creativity and old-fashioned boldness.

Jamie Burritt, the director of Vocalis, said the singers had been planning their first English tour, and the schedule took them into the festival’s orbit. “We had booked a venue in Cambridge just for a concert,” Burritt said. “The director of music said, ‘You should try to get on the official festival schedule.’ I knew that would be a tough go, seeing that we’re this random choir from Buffalo.”

Luckily, he tried anyway.

“We put forward our best recording,” he said. “And we created a unique packaging. So that when it arrived at their desk, it stood out. We worked with a woman from the Roycroft who creates her own books from scratch – paper, binding, everything. It arrived looking like a little package. It was all this fine craft paper with our information inside. The CD sat in this little drawer. It was super cool. It made an impression.

“That got their attention. But obviously, they wouldn’t have said yes if they didn’t think the quality of the music was there.”

Vocalis’ concert will take place Aug. 1 in the Church of Our Lady and the English Martyrs, a Catholic church that commemorates the Catholics executed during the reigns of Henry VIII and Elizabeth I.

The concert is titled, “Journey in Song: American and European Choral Music, Past and Present.” It includes not only music by Renaissance composers Palestrina and William Byrd, but also music by Samuel Barber and Ralph Vaughan Williams.

“And Dolly Parton!” the Cambridge website exults.

The Parton song is “Light of a Clear Blue Morning,” arranged by choral master Craig Hella Johnson.

“They asked us to do a program with American music on it,” Burritt said. In addition to Parton, Vocalis also will be singing some hymns and spirituals, as well as Stephen Foster’s “Nelly Bly.”

The rest of Vocalis’ British tour looks like something out of “Downton Abbey.” One concert takes place in the 1839 Southwark Cathedral,near Shakespeare’s Globe Theater. Vocalis also is singing at the awe-inspiring Ely Cathedral, built in the 7th century by Benedictine monks. The tour ends with a Sunday Eucharist service at Old Royal Naval Chapel in Greenwich.

In planning the tour, Burritt acknowledged the invaluable assistance of Drew Cantrill, the British former music director at St. Paul’s in Buffalo. As a former St. Paul’s choirboy, Burritt knew his way around the Anglican church culture.

“You can’t just call Ely and say, ‘Can we do a concert?’” he said. But the church doors open, he explained, when a choir offers to sing at services. “Then you’re there, and you can sing in these amazing spaces. You sing for them, and you’re getting the opportunity to sing with these glorious acoustics. It works really well from both sides – all these cathedrals, this tradition of Evensong in English cathedrals. It opens up opportunities for you to sing in these spaces.”

The English appearances, particularly the Cambridge concert, will go a long way toward helping the singers of Vocalis make their voices heard.

“It’s been a real sort of journey,” Burritt said. “The past four or five years have been great for us. This year looks like a nice verification of all the hard work – not just by me, but everyone involved. It’s a really great sort of feather in our cap, for our first 12 years.”