It was two minutes before 8 p.m. by the town clock, and Upper Marlboro's monthly commission meeting was about to take place before an unusually large and attentive audience of 30 townspeople.

Roberta Strine, citizen, tiptoed up to Helen Wilson, town commission executive, and handed her a thick roll of papers held by a rubber band. Wilson, a big-boned woman in a square-cut blue dress who could fit easily into the British gentry, unfolded the papers, glanced at their title and hastily shoved them under some folders.

She apparently wanted to draw as little attention as possible to the fact that she and fellow town commissioner Ruth Buck had just been given notice they were being sued by a group of citizens headed by the town's third commissioner, Jess Smith. The suit asks the Prince George's Circuit Court to declare invalid Upper Marlboro's provisions for registration and voting, and claims $150,000 in damages from Wilson, most of it to be paid into the town treasury.

All the group really wants to do is to make it easier for the residents of Upper Marlboro, population 300 (not including jail inmates), to register to vote in town elections. The story thus far:

Last June, Debbie and Daniel Brown, who moved here seven years ago, contested the fact that registration for local elections was held only four hours every other year.

At a meeting on June 8, commission executive Wilson agreed that as of July 1, registration would be made available every working day from 9 a.m. to noon. At least, that's what the Browns, recently elected commissioner Smith and several other citizens present at that meeting and the minutes for the meeting all declare.

But on July 1, when Debbie Brown and two other residents showed up to register, they were turned away. Wilson now says that new voters will be able to register, as usual, only on one day prior to the next scheduled elections -- in January l983.

"I did not say there would be open registration, your witnesses are lying," Wilson told Debbie Brown at Tuesday night's meeting. Dan Brown, a boyish-looking businessman who was under strict orders by his lawyer to keep a civil tongue, squirmed in his seat.

When he and Debbie Brown were looking for a quiet, prosperous town in which to bring up their three children, Upper Marlboro stood out as the logical choice. "We couldn't have been more pleased," Debbie said of the tranquil, horsey neighborhood.

Brown never thought he would have to worry about anything other than his job as manager of an equipment rental agency in Oxon Hill. "I wasn't particularly interested in getting involved in the politics of this place," he recalled. "But when they tell you you can't vote . . . you really have to do something about it."

Commissioner Jess Smith, who was elected in January, has other reasons for filing suit: He is worried that someday he may be held responsible for the irregular way he says the town is run. Town laws, he says as an example, could successfully be challenged because they are not properly registered with the state.

Another issue in the lawsuit against Wilson and Buck is alleged overspending of town money by at least, Smith says, $36,000.

As the discussion between Wilson and Debbie Brown grew heated at Tuesday night's meeting, a stout elderly man with a walking stick and a waxed handlebar moustache chomped on a piece of gum more and more furiously. His face was florid when he burst into the discussion. "I can't remember when there was so much commotion here," he said.

"I think it's about time our elected officials protect themselves and crack down. There's no reason for all these people to butt in here!"

The man was Dr. Albert Cahn, a close friend of Mrs. Wilson and her husband, and a strong defender of tradition. Hostility between the "newcomers" and the members of Cahn's generation seemed more irreconcilable as the evening progressed.

Anna Buck, elections supervisor and cousin of Ruth Buck, produced an anonymous letter she had received last month. It called the Bucks and Wilson "three old ladies" and described Upper Marlboro as a "pooptown."

"I have my suspicions as to who wrote it," she said, after reading the letter into the record.

Danny Brown felt he had been alluded to. "Can you imagine, my using the word 'poop' ? " he asked later.

"Are you going to let me register?" Debbie Brown asked. "No we are not," said Wilson. "I just can't see why there should be any hurry. We are going to do it, but not right now."

The town attorney, Ralph Powers, who will defend Wilson and Buck in the suit, thinks his clients have a case. "There is no law I can think of that dictates a town has to have registration more often than it says in the charter," he said.