If you only know Richard Thompson from his recorded work, it's easy to get the notion that he's a regular Gloomy Gus. Song titles like "A Poisoned Heart and a Twisted Memory," "Long Dead Love" and "She Twists the Knife Again" are typical of this British folk-rocker's approach to romance.

What a surprise it is, then, to encounter this 42-year-old singer-songwriter onstage and discover his sparkling deadpan wit. With the receding hairline, tidy beard and odd vest of a bohemian academic, Thompson came to Baltimore's Senator Theatre in April and introduced the songs as if he were a vaudeville emcee from his childhood days in suburban London. With the droning voice of a BBC announcer and the twinkling eye of a prankster, he introduced "Now That I'm Dead (I Can Finally Make a Living)" as a prime example of "Boris Karloff Egyptian rain-dance music ... a true story about the music business."

"There is some humor on the records as well," Thompson protests over the phone from a tour stop in Michigan, "but maybe it's too hard to find among the gloom-laden textures. I don't know why my shows are funnier than my albums; maybe it's because comedy songs don't work on record the way they do onstage. On record, a funny song sounds flippant, and after you've heard it more than once, you've gotten the joke. Gloom, on the other hand, goes on forever."

Thompson's newest album, "Rumor and Sigh" (Capitol), marks a significant breakthrough for him, because for the first time he has integrated the irreverent wit of his live shows and the gloom-and-doom of his best recordings into the same songs. For example, the album's first single, "I Feel So Good," is the story of a kid "old enough to sin but ... too young to vote" who has just been released from prison and plans to celebrate by breaking "somebody's heart tonight." With its jaunty Celtic-rock rhythms and irresistible organ hook, the song at first comes across like a joke about a know-nothing kid, but by its end the kid becomes too real to laugh at.

"I like songs like that," Thompson says, "where you don't know quite what they are or where they're going. I like a song that first appears to be funny and then turns around and stabs you in the gut. I like deception. If the humor is ironic or subversive, you can lure the listener in and hit him over the head before he's had time to realize what's happening. A musical mugging."

That happens a lot on "Rumor and Sigh." Like his hero Randy Newman, Thompson adopts the personas of characters who are not very distinct from himself but who often express opinions very different from his own. In "Read About Love," for instance, the singer is a 15-year-old boy who can't understand why his girlfriend isn't as cooperative as the women in Hustler magazine. In "Why Must I Plead," Thompson plays a cuckolded husband who begs his wife to fulfill her marital obligations. In "God Loves a Drunk," he takes the role of an alcoholic who asks us to laugh at his stumbling falls one too many times.

"I don't think I've ever written a very direct song," Thompson confesses. "It's more interesting for me if it's fictionalized. In fiction, you can express an idea from different angles; you can even express a viewpoint that's the opposite of your own. That can actually be more effective because it doesn't sound as if you're trying to get the audience to like you. It's theater. You're still trying to convince the audience that you are that person, but when the song ends, the lights go out and the curtain comes down, the audience realizes that you're not that person -- or at least you hope they do."

Most of Thompson's characters are distinctly British. A song like "Don't Sit on My Jimmy Shands," for example, might not make a lot of sense if you don't know that Jimmy Shands is the Scottish counterpart of Lawrence Welk. More accessible is "1952 Vincent Black Lightning," but it still helps to know that the title refers to the most revered of British motorcycles.

"That song was the result of a conscious decision to use an object that had some British mythology to it," Thompson explains. "So much of the mythology in European pop music is imported from America; I wanted to use something distinctly English. I'm English, and to be sincere as a writer I have to write about English stuff. I grew up listening to Jimmy Shands, and I sort of like him, even though I know I shouldn't.

"When we started Fairport Convention," Thompson says of the band he founded in 1967, "we were very interested in the lyrics of American writers like Dylan, Phil Ochs and Richard Farina. Eventually, though, we realized it's hard to be a kid from the London suburbs and write about the Mississippi Delta. We always knew we'd be secondhand if we were to become a blues band. So we turned our attention to traditional British songs, and when we started writing our own songs we based it on that tradition. We found that not only was it more valid to write about something you understand, it was a lot easier too."

Thompson brings his band to Wolf Trap's Filene Center tonight and to Baltimore's Pier Six Concert Pavilion Friday. In addition to his own albums, Thompson can be heard as a guest guitarist on this year's "Cajun Conja" (Rhino) by Louisiana's Beausoleil and on last year's "Invisible Means" (Windham Hill) as a member of the avant-rock quartet French Frith Kaiser Thompson.

"The songs I write and sing for that group are quite different than the songs on my own albums," Thompson admits. "It's the wackier, the weirder stuff. It's nice to have an outlet for that side of my music, but I also do it because it's fun. They'll try anything."