John Hanson Savings and Loan, Inc., a thrift institution based in Forestville, has reached an agreement with Giant Food Inc. to establish a full S&L branch inside Giant's large supermarket in Lanham.

If approved by Maryland regulatory authorities, the S&L-within-a-grocery store apparently would become the first such financial institution lacation in the Middle Atlantic states.

Gerald Holcomb, chairman of the John Hanson Service Corp., a subsidiary of the state-chartered S&L, said an application for the new branch would be filed shortly. If the Lanham "experiment" proves to be a success after a year, the S&L might move to open other similar operations inside food stores, Holcomb added.

Hours of the proposed branch would be about the same as that of the supermarket, which means that the S&L would be open on Sundays. Another suburban Maryland institution, Standard Federal S&L, recently opened three of its branches from 10 a.m. to 3 p.m. on Sundays, when virtually all financial institutions have been closed.

Holcomb said John Hanson S&L personnel would staff the new location and that there would be no automatic teller machines. He said some S&Ls in Western states previously opened similar branches.

In the Washington area, several S&Ls or banks have opened automatic teller machines inside or outside supermarkets and drug stores in the suburbs. American Federal S&L opened a special counter inside a Spring Valley A&P store which permits its customers to make deposits or withdrawals. A&P personnel handle the transactions.

A stockholder-owned S&L, John Hanson was reorganized in 1962 and since has grown into an institution with assets of about $125 million and seven offices.

Holcomb said the Giant branch could be opened within 60 to 90 days, if approved by the Maryland S&L regulatory agency.