There’s always been a sort of recital-esque vibe about Jethro Tull, Ian Anderson’s English progressive-rock band, whose classically tinged folk-rock seems closer to repertoire than popular-song catalog. But that’s never been more the case than with Anderson’s current tour, which plays Durham Saturday night.

It’s a show with a specific mission – to present Tull’s 1972 rock-opera suite “Thick as a Brick” in its entirety, followed by the just-released sequel “Thick as a Brick 2” (EMI/Chrysalis Records). So don’t go to the show expecting to hear “Aqualung,” “Bungle in the Jungle” or anything else not on the two “Brick” albums.

“There’s not a millimeter of extra space, no,” Anderson says with a laugh, calling from his home in England. “It’s a production very much focused on these two albums back-to-back, from 8 to 10:30 with a 20-minute intermission, after which we allow the audience to run screaming for the exit. The idea of throwing in a few hits is not something I’m prepared to do. That’s way past my bedtime and it’s a very physically demanding show. So for me and the band and the audience, enough is enough.

“It’s a set repertoire, with some built-in moments for improvisation or flights of fancy. The whole thing does run like a Broadway musical, things go on the button.”

The sequel revisits Gerald Bostock, fictional protagonist of the original “Brick” album 40 years ago. Various songs on the new album ponder whether or not he became a banker, soldier or vagrant, and they’re tinged with the wistful regrets of contemplating roads not taken.

“When I made this album, I drew on the experiences of others,” Anderson says. “I know a few other people who have had deep regrets. I hope it had nothing to do with me being their best man, but they made some unfortunate choices about life partners. So I drew on the regrets other people talked about, although I’d never betray them in song. They’re disguised enough that no one would hear something and feel embarrassed.”

By now, Anderson himself isn’t much for regrets, having had an enviable career over the past four decades. He does, however, have one major regret about Jethro Tull: the name.

“That wasn’t a choice so much as something I let happen,” he says, still groaning at the memory. “I regret that I accepted the name my agent suggested in February 1968 – ‘Let’s be Jethro Tull this week’ – which went up on the Marquee Club, and it stuck. Later we found out that it wasn’t a made-up name, but the 18th-century agriculturalist who invented the seed drill. That did not fill me with happiness, to have a band named after a dead guy. I sort of regret that.”

One immediately apparent aspect of the new album is how kind the years have been to Anderson’s voice. He’s 64 now, an age when singing voices tend to calcify, but he sounds much the same as he did in 1972.

“I’ve probably lost a tone or so of vocal range as I’ve aged,” Anderson says. “But that happens to everybody. The one and only Sinatra show I saw was long past his best, but I’m still glad I got to see him. Rod Stewart, Paul McCartney, Elton John, Ian Anderson, we all know we’re not what we were. But we can still deliver 80 or 90 percent, and be content with that as we approach our seventh decade.

“Luckily, I’m not just a singer,” he continues. “I’m also a guitarist and flautist, and I compensate by doing those better than I did in my 20s. It’s a tradeoff. I can still sing the songs in their original keys, just not with that youthful quality of my 20s. Rock singers generally don’t fare so well because we’ve not had proper training. But like David Bowie and a few others, baritone is my range. What I’ve lost from the top, I’ve gained at the other end, lower notes I did not have the power for before.”

Anderson is also lucky in that he is associated closely enough with the Jethro Tull trademark to be able to perform in either guise, band or solo.

“It’s a simple demarcation in my own mind,” he says. “I’m like a giant cornflake, a cereal product with a number of brand names for strawberry, banana flavor, whole wheat. So there’s orchestral Jethro Tull, Christmas Jethro Tull, plain ol’ Jethro Tull playing classics you hear on American radio. So the brand name applies to what flavor of Ian Anderson it is. It makes little difference to me. Sometimes I have to step outside and see what’s on the marquee to remind myself.”

Menconi: 919-829-4759 or blogs.newsobserver.com/beat