POP MUSIC REVIEW : Tull Still Has the Moves If Not the Voice : The British band puts on a dynamic and dramatic show at Irvine Meadows. But leader Ian Anderson’s vocals have considerably diminished with the passage of time.

“Age isn’t everything. Age is (expletive) nothing at all,” Ian Anderson mused defiantly during a pause in the proceedings as Jethro Tull brought its 25th Anniversary Tour to Irvine Meadows on Saturday night.

At 46, the British band’s leader remains enough of a showman to almost have backed up those words. One of the most accomplished masters of the rock ‘n’ roll stage, Anderson was a whirlwind of motion and a gale of highly locomoted breath, most of it blown prodigiously through his trademark flute, not to mention periodic gusts through a harmonica and a tin whistle.

It was impossible not to enjoy Anderson’s act richly as he made like a biped Pan, spinning and cantering about the stage, twirling his flute like a baton, kicking his legs high as if he were bidding to become history’s first balding and bearded Rockette, and making wild, bug-eyed faces at every turn. Anderson’s movements and his alternately fluttering and percussive sorties on flute were calculated to accentuate the drama in Tull’s music--and the band’s riff-flinging, dynamically roller-coastering sound is nothing if not dramatic.

But neither Anderson’s energy nor the festive, humorous mood of the occasion could hide the fact that bad luck, if not age itself, has robbed him of his singing voice.

Anderson developed throat problems during a tour in 1984, and on the evidence of Saturday night’s show, he never fully recovered. He didn’t have much range to start with; now he has lost any semblance of a high end and there was no suppleness within the reach that remains.

Thus diminished, Anderson was left to try to get by with a dryly declamatory, semi-spoken approach. It was saddening to see him strain, lifting his whole body whenever he tried for a note that might not have been very high in the scale but now stood at the edge of his grasp.

The 100-minute retrospective (which drew a fair number of younger fans along with a preponderance of baby boomers) clearly was designed to compensate for the fact that Jethro Tull no longer has an effective vocal presence.

On some songs that formerly had multiple verses and choruses, Anderson would sing just one, or Tull would render them as instrumentals.

The band was well-adapted to that approach. In Anderson’s flute, Martin Barre’s distinctively clean, succinct, note-shredding guitar attack and the versatile keyboards playing of Andy Giddings, Tull had an array of elements that could interlock in harmony or joust in byplay. Bassist Dave Pegg ventured some melodic passages as well in tandem with Anderson.

In such highlights as “Living in the Past,” “Bouree” (a reworking of a theme by J.S. Bach), “With You There to Help Me” and an abridgment of the album-length “Thick As A Brick,” the band gained freshness by stretching and reinterpreting familiar material rather than playing it just like the record.

Anderson, whose patter combined the urbane quality of a Sir Kenneth Clark with the ironic shtick of a snake-oil salesman, made it clear that he was there to entertain, not to present Tull’s long body of work as if it were holy writ.

It would be hard to act pretentiously on a homey if deliberately tacky stage set festooned with potted plants, pink flamingos and a wash line hung with laundry, and where the drum riser was papered over with pages from the trash-press tabloids (among the headlines: “Peter Pan A Pervert?” re: Michael Jackson, and “FBI Captures Bat Boy!”).

Tull made things even folksier by having fans brought up periodically to sit on a sofa at the side of the stage; Anderson would pour them a Perrier with a flourish while the band played on, then dart off to make his next cue. At one point, a comely young woman with one of those old-fashioned ballroom cigarette vendor’s get-ups walked on with a big red box and dispensed ice cream bars to the front rows.

But Tull’s vocal deficit eventually caught up with it, as did the dwindling strength of its material after the initial hot streak (1968-72) that established the character of the band’s sound and accounted for most of its memorable songs.

There was no new material on the agenda (Tull’s last album of new songs, “Catfish Rising,” came out in 1991; the show included just one song from the ‘80s, a decade in which Tull scored only one gold album, “Crest of A Knave”). So Tull began at the beginning with “My Sunday Feeling,” the first song from its debut album, “This Was.” Along with an acoustic traditional blues cover, “So Much Trouble,” it showcased the band’s deeper roots.

“With You There to Help Me” was the emotional high point--like many of Anderson’s most appealing songs, it acknowledges life’s painful side but is full of encouragement as it envisions more hopeful turns of spirit and feeling.

Momentum flagged with a medley of middling mid-’70s material and an overlong treatment of “Budapest,” a diffuse epic from “Crest of A Knave” that explores what has become a recurring, though not very rewarding, theme for Anderson on recent albums: that while he may not be too old to rock and roll, he is both too old and too smart to follow through on his lustful inclinations toward the pretty young things who sometimes cross his path.

“Aqualung” was served for dessert; Tull finished with the three tracks from its career-making album that classic-rock radio loves best. Barre enlivened “Aqualung” by seeking new possibilities in his guitar solo. That led into a grand intro to “Locomotive Breath” that left the band primed to explode as it hit a sustained chord as a prelude to the crunching riff that remains one of the most delicious in the annals of high-powered rock.

Unfortunately, Anderson’s singing just didn’t have the bite to carry the number, and what had promised to be a grand finale quickly grew diffuse and somewhat sloppy--even more so with the encore, “Cross-Eyed Mary.”

As another balding Brit, Pete Townshend, sang when he was still a whippersnapper in his mid-30s, “Can’t pretend that growing older never hurts.”

It doesn’t always hurt. In any case, it hasn’t hurt Procol Harum’s Gary Brooker, whose voice was buzzing through rock fans’ heads a year before anybody had heard of Jethro Tull. Fronting the reconstituted Procol Harum during its opening set, Brooker’s rich, expansive, soulful voice sounded as glorious as ever.

The acid test was “A Whiter Shade of Pale,” the vocally demanding recasting of a Bach composition that launched the band in 1967. Brooker aced that one, and gave thrilling performances of two other high-drama, voice-stretching nuggets from the band’s peak period, “A Salty Dog” and “Conquistador.” With his broad, craggy face and his whitening hair swept back in a ponytail, Brooker looked a bit like Marlon Brando circa “Last Tango in Paris.” Of course, Procol Harum prefers to dance the light fandango.

It also preferred not to be anchored solely in the past. Of the nine songs in its 55-minute set, three were from “The Prodigal Stranger,” the album that marked the band’s comeback in 1991 after a 14-year hiatus. A fourth was a new, as-yet unrecorded piece.

The “Stranger” stuff is too prosaic, lacking the sense of mystery and the swirling combination of musical elements that marked Procol at its peak (legend has it that the band was named after somebody’s cat, which in turn was named after a Latin phrase meaning “beyond these things”). However, the current lineup is potent and played both old and new stuff beautifully.

Organist Matthew Fisher, the only other holdover from the band’s glory days, may have looked as solemn as a church organist but he managed some wailing, R&B-inspired; licks along with the stately classical passages (Procol Harum always was a band with one ear on Bach and the other tuned to Marvin Gaye).

Ian Wallace, a veteran session drummer, and bassist Mathew Pegg, the long-haired son of a hairless Tull member, were a hard-hitting foundation that kept those stately numbers from slogging. Newcomer Jeff Whitehorn supplied razory guitar lines that only occasionally veered a tad too close to Eddie Van Halen-inspired shrieky intonations.

On “The Prodigal Stranger” album, Procol Harum sometimes seems to be trying to copy the polished current styles of Steve Winwood and Eric Clapton, old contemporaries who had managed to sustain success into the late ‘80s and early ‘90s. The show’s new composition, “The Last Train to Niagara,” pointed in a better direction. Though not as striking as the classics played in a very well-received set, it had that old sense of a band exploring mysteries and taking a journey into the unknown.

As far as performance goes, age really does have nothing to do with it in Procol Harum’s case. Whether the band has a future depends on its ability to further rekindle the songwriting spark that carried it in the late ‘60s and early ‘70s.