Only a fearlessly ridiculous musician can cover Britney Spears with a straight face, and Richard Thompson is a brave fool. That the singer-guitarist’s version of “Oops! … I Did It Again”- a live track from a 2002 show that is included on the new box set “RT: The Life and Music of Richard Thompson” (Free Reed) – warrants repeat listens is evidence that Thompson isn’t just another aging white guy with a guitar. And “RT” isn’t merely another career-spanning box set.

Though Thompson has recorded more than 20 albums and toured steadily since 1968, he has never penned a hit that cemented his name and face in pop ears; even if he had, the Londoner’s bearded mug, receding hairline, and fondness for work shirts make him an unlikely MTV star. Thompson’s music, too, is an acquired taste: His guitar playing can move from Buddy Holly jittery to Muddy Waters bluesy to ye olde English pastoral not only in the same song but within the same melody. But his ability to fuse different styles is the essence of his appeal.

In the late 1960s, Thompson enlivened Fairport Convention’s first five albums with his endlessly inventive guitar playing. Fairport is still regarded as British folk-rock’s best of breed, and Thompson stayed with it until departing to pursue a songwriting career in the early 1970s.

In 1972, he released his solo debut, “Richard Thompson Starring as Henry the Human Fly.” One of the backing vocalists on that album was a young woman with an angelic voice named Linda Peters. She married Thompson later that year, and the couple went on to create a stirring string of albums from 1974 to 1981. Ever since, Thompson has steadily churned out solo albums, many of them recorded for small, independent labels. Featuring his consummate guitar playing, eviscerating lyrics, and blithe wit, these albums appealed mostly to obscurity-lionizing critics and his cultlike faithful.

What makes “RT” such a treasure trove is how it slyly bridges the gulf between the Thompson devotee and the newcomer to his work. It’s less a linear summation of Thompson’s career than a snapshot collection introducing the man and his music.

The set’s five CDs are arranged thematically, touching on, respectively, Thompson’s world-weary song commentaries; his signature songs; his favorites captured in extended live workouts; his covers disc; and his hitherto-unreleased material.The material spans the period from 1968 (“Genesis Hall,” from Fairport Convention’s “Unhalfbricking”) to 2005 (“Joseph Locke,” recorded specifically for this project), and all tracks were cherry-picked by Thompson in conjunction with the Free Reed label. The disc of “essential songs” was determined by lists submitted by fans, as explained in Nigel Schofield’s genuflecting liner notes.

Best of all, few tracks gathered here are culled from the original albums, and many are performed by Thompson alone with his guitar. The version of “I Want To See the Bright Lights Tonight,” the title track from Richard and Linda’s stunning 1974 album, comes from a 1979 Rotterdam concert, complete with a muscular Linda chopping through this rousing working-for-a-living, drinking-to-live anthem.Thompson turns the noisy opening track portrait of grief from 1983’s “Tear-Stained Letter” into a churning, playful solo performance, massaging his lines’ sibilant musicality – “Well my head was beating like a song by the Clash / It was writing checks that my body couldn’t cash”- into such a buoyant cheer that the audience eventually takes up the chorus in unison.

Thompson has always been a hard pill to swallow, because he favors songs about relationships shattering and cynical observations of human selfishness. But his joviality shines through on the covers disc. He has a blast interpreting Squeeze’s “Tempted,” Plastic Bertrand’s “Ca Plane Pour Moi,” and a Who medley of “My Generation,” “Can’t Explain,” and “Substitute.”

Something about “Oops! … I Did It Again” lingers in the brain longer that it has any right to. Thompson pares down the original’s post-human production into jangling guitar propulsion. His haggard voice twists the coquettish chorus into something piercing, and by the time he sighs the coy tease “I’m not so innocent,” it becomes a weary confession. It’s a daft interpretation of the song, one that has the audacity not to scoff at disposable pop but mine something genuinely affecting out of it. Yes, only a brave fool would dare it, and music – if not the world – could certainly use more like him.