How does the Mormon Tabernacle Choir land top-notch guests? Here’s the man to ask.

He’s a diplomat, amateur psychologist, negotiator, relationship counselor, fashion consultant and grief counselor. He’s sat around the table with Muppets, ambushed a TV aristocrat at the airport and made Walter Cronkite an offer he couldn’t refuse.

He’s Ron Gunnell, the assistant to the Mormon Tabernacle Choir’s president who is responsible for booking guest stars for the choir’s Christmas concerts and other special performances.

Hugh Bonneville, the British actor best-known for his portrayal of the Earl of Grantham on the popular period drama “Downton Abbey,” recounted with a chuckle how Gunnell extended the invitation to narrate this year’s show. (The three-performance run begins Thursday night.)

“I was passing through the Salt Lake City airport a year ago and this man leapt at me and said, ‘I’m the guy who wrote you,’ ” Bonneville said.

In a recent interview at the Salt Lake Tabernacle, Gunnell explained that he’d sent three inquiries to the actor’s management but hadn’t received a reply. Then, as he sat at the airport waiting to pick up the King’s Singers for their July 2016 visit, who should come walking up the concourse but Bonneville and his family. After a moment of indecision — “I was just beside myself” — he introduced himself. Bonneville encouraged him to contact his agent again. Gunnell went a step further: He called actors Michael York and Martin Jarvis, former choir guests whom he knew to be friends of Bonneville’s, and asked if they’d mind putting in a word.

That combination of resourcefulness, persistence and chutzpah typifies Gunnell’s approach. Advised by Angela Lansbury’s agent to write her a letter, he instead sent roses and a note. (The stage and screen legend not only accepted the invitation to appear on the 2001 Christmas concert, she became a close friend; Gunnell sat with her at the funeral of her husband of 54 years.)

“Every organization that works with high-caliber guest artists needs a Ron Gunnell, but not every organization is as lucky as we are to have someone so dedicated and able,” music director Mack Wilberg said. “Ron’s abilities extend well beyond being able to secure the best and brightest from the music world to perform with the choir and orchestra. He has the unique ability to form trusted relationships with our guest artists that last well beyond their performance in Salt Lake City. Because of Ron, our guest artists become like family.”

“Ron can get anything from anyone,” former music director Craig Jessop said. “No one hosts better than Ron.”

Gunnell supposes his knack for diplomacy comes, in part, from the challenges of his upbringing and lifelong desire to be a peacemaker. After a traumatic early childhood, he and his twin sister, Ronda, were adopted at age 4 by Don and Alberta Gunnell of Logan. The family moved to Orange County, Calif., when Ron and Ronda were about 10. He studied at Ricks College, now known as Brigham Young University-Idaho, and served a church mission in New York City before transferring to BYU in Provo, where he met Wilberg and Jessop in the a cappella choir.

He joined the Tabernacle Choir as a baritone in 1996 after a career in benefits management and business consultancy. When The Church of Jesus Christ of Latter-day Saints opened its 21,000-seat Conference Center in downtown Salt Lake City in 2000, then-church President Gordon B. Hinckley was concerned about how the choir would fill such a large building for its Christmas concerts. (The choir’s regular home, the Salt Lake Tabernacle, seated about 6,000 at that time.) “Empress of Soul” Gladys Knight, a prominent Mormon, was recruited as the soloist; Mac Christensen, then president of the choir, asked Gunnell to invite his friend Roma Downey, star of the filmed-in-Utah series “Touched by an Angel,” to narrate the concerts. “We filled the house every night,” Gunnell said. “We were all pleasantly surprised and a little overwhelmed with the attendance.”

After booking Lansbury in 2001, Jessop wanted Cronkite as the next guest. Gunnell was recruited again and flew to New York. He hoped to negotiate a lower appearance fee in light of the fact the choir doesn’t charge admission to the Christmas shows, but the venerable newsman’s chief of staff, Marlene Adler, wasn’t budging. “I did not know how to respond,” Gunnell recalled. Then a thought popped into his mind. “Would Mr. Cronkite be interested in conducting the ‘Hallelujah’ Chorus in front of 21,000 people with an incredible choir and orchestra?”

“You mean, actually conduct the Mormon Tabernacle Choir?” Adler replied. “Well, let’s get him on the phone.” Cronkite agreed, and Gunnell went back to Salt Lake City to tell Jessop what he’d promised.

The choir compensates guest artists and covers their traveling expenses through an endowment set up by an anonymous donor. (The choir itself, along with the Orchestra at Temple Square and Bells on Temple Square, is funded through recording and tour revenues.) Still, Gunnell wants to make sure the relationships aren’t strictly transactional. “They don’t just come, perform and leave,” he said. “We change their lives. … From the minute they step off the plane to the minute they step back on, they are royalty to me.” Sometimes that has meant coaxing Wilberg to keep the choir in the loft a few minutes longer to sing an extra song as a gift for newsman Tom Brokaw and his wife; another time it meant being the first person to greet and console soprano Deborah Voigt after she learned of the death of her beloved aunt.

“For it to work, it really has to be genuine love,” Gunnell said. “I try to think of everything, to put myself in their shoes, to extend every possible offering I can think of so they feel genuinely cared for.”

“No experience prepares you to perform in a 20,000-seat auditorium,” said Broadway star Santino Fontana, who has sung with the choir three times. “Ron was kind of my guide to all of it. He made sure I was comfortable. … I felt incredibly well taken care of by Ron and the choir.”

On a couple of occasions, Gunnell has written letters to the performers who have come to consider him and the choir as friends, because he wanted to offer them additional context on controversial situations. Again, “I put myself in the shoes of the artists,” he said. The first such instance followed the November 2015 church policy barring children of same-sex couples from baptism and other rites; the other concerned the choir’s performance at President Donald Trump’s inauguration ceremony in January. A long conversation with producer David Foster, who was among the many high-profile artists who declined to participate, “helped solidify my thinking,” he said. Regardless of what he or any of the singers might have thought of this particular president, they had been invited to participate in a historic and constitutionally mandated ceremony. “We were there to celebrate the peaceful transition of power … as we have done time and time again,” he said. “It wouldn’t matter who was elected. Our job is to share music, joy and love.”

Gunnell gave up his singing spot in 2010 because of the increasing demands of his administrative assignment. “I do miss singing, as any choir member would tell you,” he said. “But this assignment is overwhelmingly thrilling. Even though I’m not singing, I feel the collaboration and support. I still feel a part of it, maybe even more so.”