LONDON (AP) _ Living to be 100 is not always desirable, according to a handful of those that made it.

Michael Bury, a lecturer in sociology at London University, asked 100 British centenarians if they were glad to have lived so long, and 74 said yes, 18 said no, and 8 did not know.

The size of the negative response, particularly in a group that had volunteered for the survey, ''indicates that long life is not a clear-cut blessing,'' Bury said.

Writing in the current issue of New Society, a weekly London magazine dealing with social issues, Bury said he and a research assistant, Anthea Holme, are making a computer analysis of questionnaires filled out by centenarians for a British television program.

A stress-free life, hard work and a good diet were the most frequent reasons cited for longevity by the 100 centenarians querried, Bury said.

The survey found that women are far more likely than men to make it to the century mark - 81 to 19 in the survey group - and those who do live that long tend to be non-smokers. Ninety percent of those surveyed did not smoke, Bury said.

Since the respondents were volunteers, the findings cannot be considered scientific, he said. But the replies suggest some key experiences centenarians have in common.

Bury said he had expected that the great majority of the centenarians surveyed would be women because studies have found that most men die at an earlier age.

But he said it was significant that 27 of the 81 women in the group had never been married, higher than what would be expected in the general population, and suggests that ''single women are more likely to survive to 100 and beyond.''

''Such a view is in line with research showing that marriage plays a more positive part in men's lives, in their survival and well-being, than it does for women,'' Bury said.

Among the centenarians, the oldest of whom was a 112-year-old woman, 74 said they had never smoked cigarettes and 16 were former smokers. Three of the men currently smoke a pipe and only three smoked more than 10 cigarettes a day. The smoking habits of the remaining four were not stated.

The picture regarding alcohol was less clear. Thirty-nine of the centenarians called themselves teetotalers and 12 former drinkers, but 37 classified themselves as moderate drinkers and 10 as heavy drinkers. Two were not classified.

The findings support research on the possible health benefits of moderate drinking, Bury said, ''though such evidence has to be treated with caution.''

Heredity also appears to be important. ''Overall, the age reached by the parents of the centenarians was appreciably higher than one would expect for those in their generation,'' Bury said.