SAN FRANCISCO -- Who better to headline a benefit for the local longshoremen's union than politically charged British singer/songwriter Billy Bragg?

He's a devout socialist; he's recorded the labor anthem "The Internationale"; and his latest album, which he recorded with folk-rockers Wilco, puts new music to unrecorded lyrics by rabble-rousing American folk-hero Woody Guthrie.

On Saturday, the Englishman and his motley band, the Blokes, enraptured a crowd of hard-core union members, some of them in their 50s and 60s, and young modern-rock fans at Maritime Hall here. The show raised money for the legal expenses of Robert Irminger, an Oakland, Calif., labor leader who was sued after local stevedores boycotted the Neptune Jade's cargo from Liverpool -- site of a long dockworkers' strike -- in 1997.

As it turned out, it was also a celebration -- the Pacific Maritime Association, a shipping group, recently dropped the suit against Irminger.

"This is really fine," concert-goer George Stillman, 52, of Oakland, said. "I was here to support the union. I don't know anything about this guy. But I sure think it sounds fine."

Bragg entertained the crowd with his own songs and a big helping of tunes from his Guthrie project, including several that didn't make it onto Mermaid Avenue, the album he and Wilco released this year. He talked at length about each song, cracked jokes, told sincere stories and goofed around, putting on a show that mixed a serious purpose with a rollicking good time.

Bragg strolled onto the stage with no fanfare or announcement and greeted the crowd with a happy wave before picking up his guitar. Standing alone in the spotlight, accompanying himself on electric guitar, he began the set with a passionate historical song about the Diggers, Britain's first organized labor movement.

Lest anyone forget that Bragg also has a soft and squishy side, he then addressed matters of the heart. With the Blokes behind him, he dug into the louder, more boisterous part of the evening with an unusually rowdy version of his "Milkman of Human Kindness" off the 1987 LP Back To Basics.

Still, much of the set involved, as Bragg put it, "doing Woody's work."

He explained to the rapt crowd the significance of many of the songs, and talked about the lyrics' continuing relevance in the late 1990s. He even translated Woody Guthrie into the language of modern rock.

"Woody Guthrie was a Clash fan. Yes he was. This is one I believe he wrote during his Sandinista period. Come on, everybody has one. Listen!" he said to his amused audience, referring to the pioneering group born out of the 1970s British punk scene and its eclectic three-record set from 1980.

He and the Blokes then played a stomping, call-and-response version of "All You Fascists Are Bound to Lose," an unreleased Guthrie song.

Bragg introduced "Christ for President," a song from Mermaid Avenue, by saying in his thick Cockney accent, "Listen -- if the President of the United States of America ejaculated on an article of your clothing ... well, you would keep it, wouldn't you? Jeez, I would!"

The audience followed Bragg and his Blokes through every mood change, tempo shift, joke and anecdote. Fans on the theater's packed main floor danced during the uptempo numbers; sobs were heard from the balcony when, accompanied only by piano, Bragg sang "Tank Park Salute," a bittersweet ballad about his father's death.

The five Blokes included veteran keyboardist Ian McLagan -- a member of '60s British rock group the Faces who later played with the Rolling Stones -- and Lu Edmonds, formerly of the Damned and Shriekback, on guitar. Though it was a band of veterans, they were enthusiastic ones, goofing around and even jumping offstage several times.

"That's got to be the happiest and least blasé backing band I've ever seen," audience member Laurel Savino, 30, said.

The group seemed to take pride in creating arrangements and sounds entirely different from Bragg's recorded versions of the songs.

For example, "Way Over Yonder in the Minor Key" (RealAudio excerpt), a sing-songy folk song from Mermaid Avenue, became an extended honky-tonk hoedown.

Bragg updated the lyrics to an old favorite, "Waiting for the Great Leap Forwards," to include presidential interns, Jesus Christ, the Republican party, fascism, former Chilean leader General Augusto Pinochet and, of course, Guthrie.

That finished the regular set. But Bragg and band returned almost immediately to play the plaintive "A New England" and "The Internationale," the early 20th century organized-labor anthem.

The hall echoed with fans singing along. The younger folks knew "A New England"; the older ones knew "The Internationale."

Bragg finished with "Way Over Yonder in the Minor Key," with the band pretending to close the song perhaps half a dozen times, waving goodbye and filing offstage.

Time and again, Bragg came racing back like a naughty boy fleeing his bedtime, with the band tumbling back onto the stage behind him. He'd snatch up his guitar to pound out a few more bars, giving everyone a little bit more.