BIDDEFORD – Maine’s oldest diner, a landmark where mayors and millworkers have eaten side by side for nearly eight decades, is under contract to be sold.

The 15-stool Palace Diner has been on the market for nearly a year, according to owners Rick and Jo Bernier. A prospective buyer recently placed it under contract after the price was reduced to $125,000.

The diner has had only four owners since Louis Lachance of Kennebunk got into the diner business with his brother-in-law Orville Pollard, whose family built the diner at their shop in Lowell, Mass. In 1927 the two trucked the diner to Biddeford, then a booming mill town.

It is the last surviving diner built by the Pollard shop and the oldest of the five eateries in Maine that truly can be called diners, according to Will Anderson of Bath, author of “Lost Diners and Roadside Restaurants of New England and New York.”

The Berniers bought the business in 1997, but said eight years of 12-hour shifts – with Jo behind the counter and Rick at the grill – has been enough. They declined to name the buyer until the sale is completed.

Palace Diner customers this week said they hope the new owner doesn’t make any drastic alterations to the small restaurant.

The real estate agent handling the sale, Norm Parisien of Signature Realty in Saco, wouldn’t identify the buyer, but said it is a Maine resident. Parisien said it is his understanding that the buyer plans to keep running the diner as is.