For years, animal-rights activists have been trying to get New York City to ban horse-drawn carriages—as London, Paris, Key West, Santa Fe, and even Beijing have done. Now People for Ethical Treatment of Animals publicity crusader Dan Mathews is in town to make it happen.

Mathews has been recruiting celebrity backers and, reporter in tow, confronting the drivers in the park himself. “Anybody can see that this horse is not happy. This animal is in shackles!” Mathews scolded a driver who identified himself as Tony Moran, a stocky, gray-fringed Queens resident whose brogue hails from the west of Ireland. “Who are you to tell me if my horse is happy? Maybe you should learn a little bit about how these horses live,” Moran scoffed. Others drivers gathered to support their mate, and one yelled from his carriage, “You’re harassing my customers!” Mathews confided later, “They’re on their best behavior because they see there’s a reporter here. Otherwise,” he added with barely concealed glee, “they could be violent.”

Mathews has been focusing on the issue since Queens City Council member Tony Avella introduced carriage-ban legislation in December. In the past couple of years, spooked horses have been involved in several traffic accidents, resulting in one equine fatality and occasional human injury. In February, a horse named Clancy died in its West Side stable, apparently of colic. A new documentary,Blinders, shows cramped stable conditions that seem notably unpleasant.

Yet Mayor Bloomberg and City Council Speaker Christine Quinn are staunch allies of the tiny industry (68 carriages, 220 horses, and 450 jobs for drivers and stable workers). Carolyn Daly, a spokeswoman for the Horse and Carriage Association of New York, denies PETA’s charges, calling Mathews and his cohort “animal fanatics with an extreme agenda.”

Mathews’s turd-in-the-punch-bowl style, especially about fur, has become the stuff of scary legend during Fashion Week. He also led PETA’s famous occupation of Anna Wintour’s office. “He’s courageous,” says Alec Baldwin, one of the celebrities—including Pink and Cheryl Hines—who are supporting a carriage ban. “If people in the entertainment business put themselves out there and take a stand, they want it to count—and Dan is extremely clever and effective about ways to make it count.” Alexis (daughter of Martha) Stewart recently sent a PETA carriage “fact sheet” to Bloomberg, explaining how she’s “horrified and depressed” by the cabs. Mathews has other strategies, too: He recently sent a letter to Deputy Mayor Linda Gibbs accusing her of ethical lapses, charging that her husband’s firm is lobbying for the industry, but the mayor’s office says he’s wrong. (In fact, a colleague of Gibbs’s hubby, Tom McMahon, represents the carriages freelance. And Gibbs had recused herself on carriage matters. Still, the issue will be taken up March 18 by the Conflicts of Interest Board.)

Back on Central Park South, Mathews was mixing it up. “What you’re doing is disgusting,” he railed at Moran, prompting a stylishly dressed lady to stop and chime in, “You are so right—it is disgusting what they’re doing.” Mathews grinned. “Anybody with any scruples can see that this is not what nature intended for a horse—even a lady wearing a fur collar.”

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