Alan Cumming separated the stallions from the clotheshorse with his red sheer blouse, Capri pants and clogs sans socks at the Roundabout’s benefit black-tie performance of “Follies” Monday.

His design for living definitely overshadowed the by-the-book evening wear of Matthew Broderick, Nathan Lane, John Slattery and Anthony LaPaglia, not to mention anything seen on Natasha Richardson, Marisa Berenson, Blythe Danner or Sarah Jessica Parker.

Bernadette Peters was skedded to host the Roundabout’s salute to Stephen Sondheim, but having landed a movie gig in Ireland, she sent a video to Cipriani’s in her place.

“I wish I was Bernadette,” Elaine Stritch cracked from the dais of the post-perf party. “It’s so cool to send in that video. But I’m here!”

While she was on the subject, Stritch recalled going “up on a line” when she first performed “I’m Still Here,” Carlotta’s survivor anthem from “Follies.” Don’t worry about that, Sondheim told her. “Yvonne de Carlo went up every night,” he said of his original Carlotta circa 1971.

The Roundabout isn’t finished with Sondheim. Next fall, its artistic director, Todd Haimes, is giving the composer’s killer tuner “Assassins” its first Broadway outing. “Now that’s bravery!” Sondheim told the crowd.