Ridgewell's Caterer Inc., the largest and most established caterer to Washington's elite, is extending its lavishly prepared platters to another state.

The Bethesda-based firm's distinctive purple trucks soon will be seen in Philadelphia and King of Prussia, Pa., where the company opened offices last week in its first venture outside the Washington area.

The opening of a Philadelphia office is the first of Ridgewell's planned moves to several other eastern and midwestern cities in the next five years, according to Jeff Ellis, 41, president of Ridgewell's.

"Our strategy is to try to identify cities that closely resemble the demographic and business opportunities that Washington has," Ellis said.

"Philadelphia has the demographics in that there is a definite number of businesses and corporations. There are the fund-raising types of events that Washington has been so acclaimed for, and there are also the cultural and social activities," Ellis said.

Ridgewell's business is 85 percent business-driven, Ellis said. "Most of our catering is at the opening of new building, sales promotions and general business advertising events," he said.

Ridgewell's main Philadelphia facility will be a 20,000-square-foot warehouse with a kitchen, bakery, showroom and sales office. In addition, Ridgewell's has renovated a Society Hill town house to use for conferences and as a showroom.

The catering firm is planning another new food-service venture in Philadelphia and Washington, according to Ellis, who would not give any details on its nature.

Ellis also hinted at another venture within the next year that would involve "more than just catering. It will be in the eastern region and will be partially food-related," he said.

Ridgewell's was founded in 1928 by Charlie Ridgewell, an English butler and chef who began serving at many private homes and embassies. Ridgewell sold the company to son-in-law Clarence Ellis in 1946. Ellis' twin sons, Bruce and Jeff, took over in the late 1960s after each spent time in the service.

Ridgewell's was acquired from the Ellis brothers in April 1984 by Carson Pirie Scott & Co., the Chicago-based firm with 24 department stores, a food-service and lodging group and a floor-covering wholesaler.

Carson, a publicly traded company, last year reported net earnings of $27.2 million ($5.56) on sales of $1.2 billion. Ridgewell's never has disclosed its sales and earnings figures, but Ellis said the company's sales last year exceeded $14 million and that it has experienced 15 to 20 percent growth in the past 15 years.

The Philadelphia office has more than 20 full-time employes and about 50 subcontractors, while the Washington office has more than 80 full-time employes and 800 subcontractors, including waiters, waitresses, car-parking attendants and announcers. More than 6,000 Washington-area parties a year are catered by Ridgewell's, while the company performs 8,000 additional catering services.

Heading the new Philadelphia operation is the director of catering operations, John Dougherty, who was formerly in charge of the food-service operation at the University of Pennsylvania.