Lily Allen was halfway through the first song of her concert at the Orpheum Theatre on Saturday when it became clear just how much the audience at the first of two Los Angeles shows this weekend was on her side.

The show, like her new album, opens with the title track “West End Girl,” a song in which Allen sings about the night her husband called her from out of town to tell her he wanted to open their marriage to other lovers.

The song ends with a spoken-word segment, Allen’s crestfallen comments from her side of the call, which live on stage introduced a rowdiness to its story.

“Hang up!” a man shouted from somewhere in the theater on Saturday.

“[Bleep] him!” another joined in from the darkness

“Divorce him!” added a third, with more shouting similar sentiments of support.

The “him” in question is actor David Harbour, whom the English singer married in 2020. She’s said the songs are inspired by their split, but also that she took artistic license in places.

Because Harbour hasn’t directly addressed the album, and Allen acknowledges she mixed fact and fiction, we’ll use The Husband to refer to the character in Allen’s lyrics.

Still, no matter what you believe is the truth, and who but Allen and The Husband would know that, this crowd was all in for Allen from the moment her terrific new song cycle arrived in a creative production in downtown Los Angeles on Saturday.

How creative? Well, the show includes only the 14 songs of “West End Girl,” performed live in the same narrative order as they are on the record. The concert clocks in right at one hour, short for any show these days, though fans looked uniformly happy as they filed out just after 10 p.m.

The opening act was similarly unique. The Dallas Minor Trio, three cellists, performed string arrangements of Allen’s earlier hits, which, OK, that’s cool. But it also felt quite sweet as fans made that part of the night their own, singing along to the instrumental arrangements of songs such as “Smile,” “LDN,” Hard Out Here,” and more.

Then there was the theatrical aspect of the Lily Allen Presents West End Girl, which draws upon her recent work on the British stage in London’s West End theaters.

When “West End Girl” opened the show, Allen slipped between the green stage curtains and stepped into the spotlight in front of them: Simple, elegant, a classy theater look. The phone rang for her dialogue, and she, in a yellow jacket and skirt, sat on the carpeted steps and answered a vintage red rotary phone.

Little by little, the stage and performance evolved. For “Ruminating,” the curtain opened a third of the way as images of Allen’s face were projected on it while she sang of sleepless nights and intrusive thoughts about her partner.

The curtain was two-thirds open for “Sleepwalking,” which revealed the interior of a mid-century flat, Allen seated on a vintage settee, a chandelier overhead.

The stage was fully revealed by the fourth song, “Tennis,” by which time Allen shed her skirt and walked the stage in a slip and heels; the lyrics envision a fight after Allen found a text from someone named Madeline on The Husband’s phone.

That number ended with a video projection onto Allen’s slip of someone’s arms wrapping her in an embrace. And so the night went, the story evolving in simple, perfect pieces, thanks to Allen and her co-creative director Anna Fleischl, who staged and directed this tour.

The audience participation, desired or not, continued at times throughout the show. During “Tennis,” most of the theater joined Allen in the recurrent line, “And who the [bleep] is Madeline?”

On other songs, the flamenco-tinged “Madeline,” the skittering drums and anxious bass of “Relapse,” they simply sang loudly along. [Or screamed the words at earsplitting volume and very off-key, as did the row of exuberant fans behind me. Ouch.]

One of the great successes of the album is how Allen and her collaborators married fun, sexy, romantic pop grooves to lyrics of the darkest moments in the lives of her and The Husband. You’d find yourself listening, or singing along to songs like “4chan Stan,” which compares The Husband to an internet creep, and scarcely notice the disconnect between presentation and content.

Other songs, such as “Just Enough” and “Beg For Me,” fit the more traditional mode of sad words, sad music. Sandwiched between them, you got “Dallas Major,” a terrifically dance-y number, in which Allen half-heartedly tries to sell herself to anonymous partners on a dating app.

For “Dallas Major,” she walked around her home in heels and a pink feather boa, dusting the lampshades and furniture. A curtsy at the end and a brief walk offstage signaled the end was near.

“Let You W/In” saw her reclaiming her strength and standing up to The Husband on what she would or would not say about the end of their relationship. “Fruityloop,” found her stronger yet, recognizing that they both may have brought their own issues to the marriage, but now she clearly saw it was never her job to fix him.

So, where does a “West End Girl” go from here? You can imagine its narrative fleshed out into a musical theater production with additional songs and characters, perhaps.

But first, there’ll be the arena tour Allen booked after all these intimate theater shows rapidly sold out. She plays the Kia Forum in Inglewood on Sept. 25.

You figure she’s got to play “West End Girl” in order as she did at the Orpheum, though there’s a much bigger stage to fill. Perhaps the album and then a second set of hits? Time will tell.