Peoples Life Insurance Co., one of the oldest businesses in the District, is seeking permission to close its headquarters here and consolidate them with those of a related company in Durham, N.C.

A spokesman for Peoples, which is owned by Capital Holding Corp. of Louisville, said the move would allow the company "to make more effective use of existing resources--people, information processing" and the like, and would result in "economies of scale and . . . operating efficiencies" for both companies.

Peoples currently has about 365 employes in its main office here. The company's spokesman, Peter Bogren, said he expects most of them will be offered positions in Durham, "though I think we can assume that not all of them would accept."

"We intend to do this in the fairest way for all concerned," Bogren said.

He said that he did not know what proportion of the company's staff would go, but sources in the industry here said yesterday they know of a number of Peoples' employes who are actively job-seeking.

Bogren said the company's proposal is pending before the D.C. superintendent of insurance. He said the company does not know when, or if, approval will be granted, and noted that Peoples will do nothing until it is.

If the proposal is approved as submitted, Peoples' administrative functions will be combined with those of Home Security Life Insurance Co. of Durham, which is also owned by Capital Holding.

Peoples will retain an office in the District, as well as its half-dozen sales offices in the Washington suburbs, Bogren said.

He added that the firm's main office building, at 601 New Hampshire Ave. NW across from the Watergate, has been put up for sale. The building, which was built in the 1950s and occupies an entire block, is considered one of the city's prime pieces of real estate. Bogren said he did not know how much Peoples expects to realize from the sale.

Peoples and Home Security are what are called combination life insurance companies, meaning that they offer a variety of different policy types and market them in a number of different ways. Peoples, as of Sept. 30, had about $5.1 billion worth of insurance in force and assets totaling $838.5 million. Home Security has $3.3 billion worth of insurance in force and assets of $271.5 million

Peoples, which was founded here in 1903, does the bulk of its business in West Virginia, Pennsylvania, Delaware and Ohio, as well as in Virginia, Maryland and the District.