In its first designer collaboration, Express has tapped Celia Birtwell to design four limited edition minicollections. The first will appear in stores April 7.

Birtwell, known for the colorful prints she designed for late husband Ossie Clark’s bohemian label in the Sixties and Seventies, later found more acclaim as a home textiles designer. Now her son and daughter-in-law run her eponymous London shop, and Birtwell has returned to the apparel world. In 2006, her line for Topshop became a runaway hit. Separately, the iconic Ossie Clark brand is aiming for a revival.

“This spring is all about vibrant prints, so we tapped one of the greatest print legends in Celia Birtwell,” said Fran Horowitz, executive vice president and general manager of merchandising and design for the $1.8 billion apparel chain. “Our design team worked closely with hers to rework the color palette so that it sits with our product in a really fresh and new way for the season.”

Birtwell, who was in Philadelphia when the deal developed, went to a local mall to check out one of Express’ 500-plus stores. “I liked their blocks of color, which seemed like the perfect vehicle to add prints,” she said from her London home. “I thought I’d be suitable for that.”

The first collection includes two silk chiffon blouses in six different prints retailing for $79.50 and one silk chiffon dress in two different prints for $128, about 15 to 20 percent more than most of the store’s offerings, but among the most fashion-forward yet. Birtwell combined some of her vintage patterns with new ones to create the styles, which have an updated bohemian vibe.

“Everything goes in circles; there’s nothing new, really,” she said. “It’s just getting the right time and place. I think people will like them because they are pretty and wearable, and affordable, which is especially important now with finances in flux.”

Express’ 100 high-performing stores will sell the pieces, which number just 250 units a store. The second collection will drop in July, and dates are to be determined for the third and fourth, which Birtwell just finished.

The designer approves of merging high design with mass market fashion. “Today there are pretty people from all walks of life, not just kids with money,” she said. “I like that.”

This story first appeared in the March 21, 2008 issue of WWD. Subscribe Today.

Birtwell also is launching a line for Topshop in June, as well as a line for British sporting goods chain Millet’s in May.

“I hate seeing all those plastic anoraks; they should be forbidden,” she said. “These clothes will blend with nature.”

The line is set to launch just before the U.K.’s Glastonbury music festival, where concertgoers such as Kate Moss and Gwyenth Paltrow don Wellies and casual gear to sit through the often rainy shows.