Escorted by armed militiamen in jeeps, a group of 32 heavy-hearted Britons was evacuated from Moslem west Beirut today, a remnant of an expatriate community that had held on in the Moslem sector during its most desperate moments.

The slaying of two kidnaped British teachers and an American hostage, in retaliation for the British-backed American air strike against Libya, and the disappearance of a British journalist last week helped persuade the hesitant Britons to pack their bags and leave. Many of the group said today they doubted they would ever return.

"Things have gone too far, too fast," said a British teacher, a close friend of Philip Padfield and Leigh Douglas, whose bodies were discovered Thursday with that of Peter Kilburn, an American librarian.

Their fate has "changed my view of staying here," the teacher added. "They were two entirely honest and innocent people who have died for causes beyond their control . . . . I no longer feel it is realistic to stay here. When it can happen to anybody, any day, for any reason, whether they be Lebanese or foreigners, just shows how things have really fallen to pieces here."

The Norwegian Embassy pulled out its staff over the weekend and other foreign communities, including the few Americans still here, were considering contingency evacuation plans.

The group of Britons, plus one New Zealander, an Irishman and a Lebanese holding a U.S. passport, had gathered at the rear entrance of the Carlton Hotel at 7 a.m. to cross into Christian east Beirut. Many were elderly, including a couple that has lived here since 1948.

Looking bewildered and fatigued, the evacuees piled their suitcases and belongings into cars and two gray buses. Flanked by jeeps, militia trucks mounted with antiaircraft guns and Lebanese police holding pistols, the convoy was whisked off to the Green Line dividing Beirut into Christian and Moslem sectors.

This was not the first evacuation from Beirut or Lebanon for a number of them, but it was the most sweeping. University professors, teachers, doctors and even journalists of major world news agencies, who had kept Beirut staffed at times of tremendous risk, are now gone from west Beirut, where westerners have been exposed to kidnapings and frequent gun battles. The exodus of British journalists, the first in Lebanon's turbulent history since 1958, seemed to signal the end of an era here.

Two British journalists, Alec Collett, 63, kidnaped on March 25 last year, and John McCarthy, seized on his way to the airport on Wednesday, are still missing. The British Council, an important center for cultural activities in Lebanon, closed and a school affiliated with Britain moved to east Beirut in recent days.

A good number of those who finally left west Beirut today, after a month of urging from the British Embassy, had stayed here out of a sense of commitment and service to Beirut. "So many of us came here to give," said an English housewife and mother of three, who taught in her spare time at a language center run by Padfield.

Her 12-year-old son, tears rolling down his cheeks, said he didn't like leaving because he would miss his friends. "I am sad we are not coming back, it is sunny here," he cried.

"It is difficult to leave when you have shared the suffering of the Lebanese," his mother said.

But the risks for Britons over the past few weeks had become too great.

"It has been an anxious time," said an evacuee who has taught English in an intensive language program aimed at preparing local students for university education abroad. "I have been staying indoors all the time, taking the embassy's advice. It has become impossible for me to work or live here without ridiculous security precautions."

The sight of elderly British residents leaving was the most touching. A thin old man with a sun-burned face lugged a rolled carpet onto his shoulder and climbed into the bus. With wide, sad eyes, he looked back one more time, as if a long vacation had finally ended.

"To live and work here has been very precious," said Joan Crooks, a teacher who spent nine years in Beirut. "To leave very loyal and wonderful friends is hard, but it is also sad to see the collapse of all that was good."