THE EXTRAORDINARY 31-year career of J. Hamilton Lambert with the Fairfax County government seems to be coming to an end. Mr. Lambert's decision to retire on Dec. 31 as county executive came after contract negotiations deadlocked, leaving the county board of supervisors singing his praises but politically unable to send his salary up as well. Apparently all the supervisors and Mr. Lambert, too, regretted this outcome, but everyone in the county can be most thankful for the remarkable accomplishments of their nationally acclaimed county administrator. When you're hailed by the likes of Jack Herrity and Audrey Moore, John T. "Til" Hazel and state Sen. Clive L. DuVal 2d, you've had a phenomenal run -- and in Mr. Lambert's case, one phenomenal rise from a young draftsman in the old courthouse to someone chosen in 1988 by City & State magazine as one of the top three county executives in the country.

Mr. Lambert's reputation is built on a rare combination of excellent technical skills, cool political savvy and a common touch with other county employees that produced solid loyalty. And however unhappy residents have been over the years about the price of living well in Fairfax, they have had it quite well throughout -- with local government services as good as any in the country and a quality of life so good that the county was bound to attract people and business in great numbers.

Individual supervisors have come and gone; all of them were served loyally, and many were protected from blame for their mistakes by Mr. Lambert. Not only has the county been well-served, but the entire national capital area has benefited from Mr. Lambert's administrative and political craftsmanship.

Although Mr. Lambert says he has no immediate plans other than ensuring a smooth transition for his successor, we have no doubt that somewhere soon a grateful constituency will welcome "J. Lambert: The Sequel."