Danny Rutigliano as Marcus Lycus, Bruce Dow as Pseudolus, Steve Vinovich as Senex and Tom Story as Hysterium and in the Shakespeare Theatre Company’s production of “A Funny Thing Happened on the Way to the Forum,” directed by Alan Paul. (T. Charles Erickson/T. Charles Erickson)

It was in Washington, history records, that Stephen Sondheim made the crucial change that sent “A Funny Thing Happened on the Way to the Forum” to Broadway as one of the pillars of American musical farce. Realizing that audiences were not plugging in to the show’s cheeky burlesque, he dashed off a new opening number here — “Comedy Tonight” — and, lo and behold, theatergoers took the cue and began to roar.

You can hear echoes of those long-ago roars again now at Sidney Harman Hall, where, of all organizations, the Shakespeare Theatre Company is reviving “Forum” in a flashy production that is at all times eager to please and, sometimes, even a little desperate to. Presided over by Bruce Dow, a blue-ribbon Shakespearean clown playing wiseacre slave Pseudolus, this version of the 1962 show is in time-honored fashion choreographically slick, rampantly silly and aggressively incorrect, politically speaking. All things considered, it’s an agreeably retro diversion.

Although some of the antics wheeze in the irony-laden modern air, and a few of Dow’s or director Alan Paul’s inventions prove labored or cloying — this is the rare occasion when pasties make an appearance in a temple of Elizabethan drama — Sondheim’s score and Burt Shevelove and Larry Gelbart’s book mostly hold up as paragons of farcical ingenuity.

“Everybody Ought to Have a Maid,” the Act 1 anthem for dirty old men of all ages, retains its gleeful snickering wit, and the “Lovely” that Pseudolus sings in Act 2 to his constipated ­co-conspirator Hysterium (Tom Story) remains one of the smartest uses ever of an age-old convention of musical comedy, the reprise.

So, let’s see: The show was minted in ’62, making it 51 years old. That qualifies as classical, right? Oh, whatever. Putting on this musical is certainly a stretch for the Shakespeare — and yes, we know, “Forum” is based on a play by Titus Maccius Plautus (254-184 B.C.). Still, it has to be a little galling for the metropolitan area’s Sondheim specialists at Signature Theatre to find the conveyors of “Coriolanus” muscling in on their turf. And yet you feel, too, for the Shakespeare, hungry to fill seats for the holidays in the nearly 800-seat Harman, which in six years of operation has not been able to supplant the 450-seat Lansburgh as, programmatically speaking, the company’s nerve center.

Stephen Sondheim’s “A Funny Thing Happened on the Way to the Forum” is now playing at the Shakespeare Theatre Company, through Jan. 5. (Courtesy Shakespeare Theatre Company/The Washington Post)

Paul’s “Forum” adorns the stage handsomely, what with James Noone’s clever rendering of a trio of Roman houses made to resemble grand cardboard cutouts, and with costume designer David C. Woolard’s cartoon-­colored togas. Josh Rhodes’s choreography for the agile young women of Marcus Lycus’s house of ill repute and the men playing the all-purpose Proteans is becomingly athletic. Adam Wachter’s leadership of the nine-member orchestra is an asset, too. And one hopes sound designer Jason Tratta is kept on retainer, because audibility in the ear-challenging Harman has never been better.

You want to be able to hear every syllable of crisp intelligence in Sondheim’s lyrics, which on the whole remain fresher than Shevelove and Gelbart’s script, admirably well-built but heavy on leering frat-house humor. Even Sondheim has trouble sustaining the joke in the coarseness of “The House of Marcus Lycus,” the long Act 1 parade of prostitutes. As all of the female characters of “Forum” are scantily clad sex workers, dullards or battle-axes, I can’t say that I’d tell my daughter in college that this is a show she absolutely needs to see.

Fortunately, though, there is a captivatingly sly performance in the guise of the evening’s ingénue, Philia, delivered by an actress whose name you’ll want to commit to memory: Lora Lee Gayer. She played the supporting role of Young Sally a couple of years back in another revival of a Sondheim musical in Washington, the Kennedy Center’s “Follies,” and as it turns out, that part barely hinted at her gift for comedy. With the gaze of one who seems far too easily distracted and a voice pitched somewhere between clueless squeak and Kristin Chenoweth, Gayer turns Philia into an endearingly desirable dolt, of the smartest kind.

Philia is the virgin in the House of Lycus — lots of virgin jokes, too, in “Forum” — who has been sold to the Roman general Miles Gloriosus (an impressively colossal Edward Watts), but who falls for the sweet Hero (Nick Verina), whose family owns freedom-seeking Pseudolus. Much zaniness occurs on the path to uniting Philia and Hero and unyoking Pseudolus. (Up and down the ranks, the cast is good.)

To streamline the farce, Paul excises the unremarkable Act 1 number, “Pretty Little Picture.” And even so, this “Forum” drags in the book scenes, attributable in part to a director and cast falling a tad too much in love with their own fooling around.

Vamping and ad-libbing can be fun — the tradition of taking liberties with the text started with Zero Mostel’s Pseudolus in the original production — but the insistence on excessive milking, of doing three bits, asides or double-takes when only one is required, not only begins to feel like self-indulgence. It also takes the snap out of the joke. In “Forum,” there’s always a decent amount of comedy tonight; no one wants to feel as if the punch line doesn’t come until tomorrow.

A Funny Thing Happened on the Way to the Forum

Music and lyrics by Stephen Sondheim, book by Burt Shevelove and Larry Gelbart. Directed by Alan Paul. Choreography, Josh Rhodes; set, James Noone; costumes, David C. Woolard; lighting, Rui Rita; music direction, Adam Wachter; sound, Jason Tratta; wigs, Paul Huntley. With Steve Vinovich, Julie Johnson, Harry Winter, Danny Rutigliano, Jennifer Frankel, Matthew Bauman, Nick Flatto and Blakeley Slaybaugh. About 2 hours and 25 minutes. Tickets, $18 to $110. Through Jan. 5 at Sidney Harman Hall, 610 F St. NW. Visit www.shakespeare-theatre.org or call 202-547-1122.