London — Margaret Thatcher, who at time of writing seemed assured of a triumphant election victory, faces what would be a daunting challenge for any British prime minister:
Presiding over a divided society which is entering an era of change comparable to the early days of the Industrial Revolution a century and a half ago.
The decline of the steel mill, coal mine, textile plant, and other old industries in the north of Britain is accompanied by unemployment and a measure of disillusion - but also, in part, by a growth of the microchip, computer, television, and other high-tech industries in the already prosperous south.
The result is social and economic imbalance, thoughtful observers here say - but opportunity as well.
The government's immediate tasks are generating jobs (13.3 percent of workers are unemployed, including 1,226,000 under 25); managing the economy (retail sales are up, inflation is way down, but manufacturing is low and the money supply is expanding faster than predicted); and keeping a credible defense (and an affordable one).
Underlying these, however, is another fundamental task: turning the impact of the microchip era from difficult transition to expanding possibilities.
''I'm not pessimistic,'' says one close analyst of the British scene for the past two decades, author and columnist Anthony Sampson. In an interview in his basement office in London's Notting Hill Gate, Mr. Sampson said he thought Britons were suited to the new wave of computer technology sweeping the Western world and Japan.
''We're good at language and at communications in general - writing, radio, television, and so on,'' remarked the author of the widely recognized book, ''The Changing Anatomy of Britain.''
''The microchip could turn out to be a good opportunity for us. It requires sophisticated minds. We may be rather good at that. Of course, it will need application and capital, as well - and it does mean changes in the way people think and live.''
For the moment, Britain remains one of the lower-wage, lower-producing countries of Western Europe.
And a wide variety of people with whom this correspondent talked in many parts of the country agreed that, despite some notable exceptions, the country is still divided by social class, mired in old ways, reluctant to make radical change, and too indifferent to the art and skills of business management.
In the Midlands, in the north of England, in Scotland and Wales and Northern Ireland, the lines of the jobless are long and unhappiness with London is high. The new factories of South Korea, Brazil, Taiwan, and other growing third-world countries have taken over steel and textiles. The Americans and the Japanese are the high-tech, consumer-item leaders.
So what is left for a country like Britain?
Decline in the same way that Spain and Portgual and Italy declined once their empires had gone?
Or vigorous renewal from within?
For all its problems, this country still has much with which to work. It has the pride and experience of an imperial past. It has a unique record of political stability, global financial skills in the City of London, and scientific invention.
In this country and elsewhere, changes being generated by the microchip are so profound that they are being compared to the coming of the steam engine and the spread of the railroads, which helped alter the way Britons thought about themselves and the world 150 years ago.
The outlines of the future are still dim. There are those who heartily dislike what they see, just as the Duke of Wellington a century and a half ago said that no good would come of railroads allowing working people to leave their homes and travel where they pleased.
But according to Andrew Neil, British editor of The Economist magazine, the post-industrial age is dawning, and nothing can hold it back.
This age has its pitfalls as well as its advantages. Most of the new factories and industries are opening up in the south of England (except for ''Silicon Glen,'' a concentration of high-technology plants in Scotland).
''This is helping to show even more clearly the gap between the north and the south of Britain,'' Mr. Sampson says. ''The area 50 miles from Heathrow Airport, down the M3 and M4 motorways, is becoming something like Boston's Route 128.
''Towns like Basingstoke, Swindon, Reading, have new high-technology factories going up all the time. People are moving there. It's a different country from the older cities of the north - Birmingham, Liverpool, and so on. Those cities are in decline, while the south grows.''
At the same time, more positive changes could be involved. Traditional ways of thinking are being shaken. Old forms of trade unionism will have to change.
Computers and word processors mean that people don't necessarily need to commute to a central location to work. Mr. Neil says that already a new breed of ''housewife programmers'' is springing up along the M4 motorway.
They are women who, in their own homes, program computers for the high-tech industries in cities like Newbury, better known for its US Air Force base at Greenham Common, its cruise missile site, and peace protesters.
''The new high technology needs flexible people and new skills in labor relations,'' Mr. Sampson says. ''Tbe main capital involved in the computing, television, and computer business is the people themselves who do the work.''
The transition to new attitudes and habits may be difficult, but it will be necessary, he believes.
The former deputy editor of The Times of London, Louis Heren, in his 1981 book ''Alas, Alas for England,'' saw some hope of success in the search for new attitudes.
''The question was, how to change attitudes,'' Mr. Heren wrote. ''How could the fraternal and generous instincts of populism be nurtured and directed for the greater good?''
He quoted George Orwell, who wrote in 1941 that ''England will still be England . . . like all living things, having the power to change out of recognition and yet remain the same.''
Needing urgent attention now that the election is over are class division, education, and business management.
Class. There are still many middle-class British people who say that class exists only in the eye of the American beholder, and that the ''Upstairs, Downstairs'' TV series was a deliberate exaggeration that, in any case, applied only to history.
''I think that more and more British are middle-class now,'' a London businessman said in conversation the other day.
Commentator David Watt writes in The Times of a ''blurring of the boundaries of what used to be called the working class'' to the point where the working class no longer automatically supports the Labour Party.
''Yes, but there certainly remain social classes here,'' says a reflective official who works for the British government in the cultural field in London and abroad. ''In a country lacking for many years sharp ethnic or religious divisions (except in Northern Ireland), class has been a collision point, and people love to hammer away on it.''
This man sees class division lessening a little.
So does Lord Nicholas Bethell, a hereditary peer in the House of Lords and a member of the European Parliament for northwest London.
While campaigning door to door to help Tory colleague Hugh Dykes defend his Commons seat of Harrow East, Lord Bethell said there were now many more self-made people in high posts in the Tory party.
''Class is not as black and white as outsiders sometimes think,'' he said. ''It is changing. It is less rigid. A local Tory branch chairman now is likely to be a garage proprietor or someone similar.''
He might have added that the current Tory leader, Mrs. Thatcher, is a grocer's daughter; and her predecessor, Edward Heath, is a carpenter's son.
Education. Mr. Sampson still sees a strong class strain here.
''About 50 percent of entrants to Oxford and Cambridge are still from fee-paying schools,'' he says. ''Most of the really top jobs go to graduates of the top public schools. It is harder to get in now, and it's more of a meritocracy.
''In the old days, if you were good at sport and your father knew one of the dons, you were set. Now, you have to pass the exams, no matter who you are - though it is still easier if you know someone or if you go to Eton or Winchester or to another school which knows how the game is played. . . .''
Business management. British companies are still slow to emerge from old hierarchies which separate managers from employees.
In Coventry, the chief executive of Jaguar Cars, John Egan, said that too many businessmen in Britain aimed for a title and a house in the country. They did not work as hard or as long as their Japanese, West German, or French counterparts.
This was changing, but slowly.
Mr. Egan abolished three of four dining rooms he inherited at Jaguar. Now, instead of one for blue-collar workers, one for white-collar staff, one for senior management, and one for top management, there is only one - and a small room to entertain visitors.
''You can learn a lot from dining rooms,'' Anthony Sampson comments. ''Yes, class in business is changing, but there is still stratification. You still can't find a big company here like IBM was in New York State when I visited it - all the employees in one cafeteria, with Tom Watson, the top man, standing in line with them.''
He goes on: ''We pride ourselves on being a nonmilitary nation, but you know, there is a military caste to our industry, in the system of ranks and privileges. When I was in the Navy there were different bathrooms for almost every rank, and too much of British industry is the same.''
Some managements here work hard to break down layers of bureaucracy and privilege. More needs to be done, Mr. Sampson says, and he asks whether the new computer age now dawning might help to break down old divisions and help create a more egalitarian society that retains its sense of excellence and compassion.