Showbiz is full of successful double acts — Abbott & Costello, Laurel & Hardy, Martin & Lewis — but behind the scenes, few partnerships have been as long-lived or effective as the 30-year collaboration between child agent Judy Savage and acting coach Diane Hardin. Together, the duo virtually rewrote the book on how to develop young talent to be camera-ready before sending them out on auditions.

Hardin, who has greasepaint in her blood (her parents met at a play, her husband is an actor and daughter Melora plays Jan in “The Office”), started as an actress. “I was also teaching classes for the Gifted Program in the L.A. schools because I loved kids, and I loved acting. So I thought, I’ll put those two together and teach children,” she recalls. When a friend suggested teaching professional children, she began with a class of 10 in a friend’s den. “It was all word of mouth and just grew,” she says.

The team was born soon after Savage started her long-running talent agency.

“I saw how hard it was for some child stars to make that transition to adulthood, and I thought, if adults get trained, why not children?” says Savage, who investigated various acting coaches and was unimpressed by the techniques they used, convinced that training kids was about more than teaching them to cry on cue.

“Back then, the word in the business was: Don’t train your children, they won’t be natural,” Hardin explains. “But Judy came and watched a class, liked what I was doing, and we hit it off. I liked her approach, that kids need to be kids first and actors second, because she always encouraged kids if they wanted to go to camp or book out for a while. She was incredibly supportive of all that.”

Soon Savage was sending all her clients to Hardin. “I’d watch their growth and progress and tell her when I felt they were ready to compete in the business,” Hardin reports. “I remember when Nicholle Tom (“The Nanny”) had this amazing breakthrough in class one night. I immediately called Judy and told her she’d really become an actor. Judy sent her out the next day for ‘Beethoven,’ and she got the part — on her very first audition.”

Although she sold her Young Actors’ Space school in 2004, Hardin is far from retired and now teaches in New York four times a year. “Judy and I changed the whole way people thought about training kids,” she says proudly.

“I could never find another Diane,” Savage laments, “although I’ve tried. She’s like the Pied Piper with kids. She has that magic touch.”