Britain, like America, is in recession, but here the slump's global and historic dimensions seem closer at hand. It is a matter of perspective. This is the home of the industrial revolution and a trading nation with a world horizon. From this vantage point, the slump seems to mark the end of an era -- the fastest period of economic growth in history -- but with what consequences no one knows.

A British banker puts it this way:

We've had an incredible 35 years since the war. You have two generations with high expectations. But now growth's slowing down -- whether here, in the States or Brazil. A major recession in the United States will be catastrophic for countries that rely on raw commodity exports. But, on the other hand, should you continue to run inflation, considering the social stresses it causes?"

Economic growth is a phrase that has ben so overused that it has lost much of its meaning. When plentiful, it acquired a bad name. Too many nasty side effects: pollution, most conspicuously. But continuous economic expansion has been the single overriding reality of postwar history. In industrial countries, leisure-oriented societies and modern welfare states resulted. In poorer countries, rising living standards have proven the most effective check on high birth rates. As people get wealthier, they have fewer children. The only other way the world rids itself of surplus population is by starvation or war.

Now, however, all major groupings of nations -- the industrialized countries, oil producers, developing countries and the Communist bloc -- face substantially slower growth, and oil is only part of the cause.

Most industrialized countries are locked in austere anti-inflation policies. The Soviet Union (and with it most of the Communist bloc) contends with not only scarce oil supplies but also a shortage of skilled labor. Oil producers could provide a big boost to growth by spending much of their higher revenues, but this seems less likely now than in 1974-75. Many of these countries no longer need new airports, hotels and hospitals; moreover, they wisely fear the social consequences of excessively rapid modernization.

Taken together, the slowdowns in individual countries are likely to be reinforcing. Perhaps one-seventh of the world's output moves in international trade. Given slack world markets, competition, price pressures and protectionist demands all will intensify. These charges should hit the so-called middle-income countries (such as South Korea and Brazil) especially hard. They depend heavily on rising export earnings of foreign exchange to buy needed imports and to service their international debts. As for the poorest nations, they may find that aid from the richest countries slows down as the rich feel a bit poorer.

There is a lot going on here that we simply don't understand. Two economists at the London Business School, Michael Beenstock and Patrick Willcocks, dispute the conventional wisdom that a stubborn wage spiral in industrialized counries has depressed profits and, therefore, the incentive for investment. They suggest that lower profit levels simply reflect new manufacturing competition from developing nations. They think the same thing happened in the 19th Century when British economic growth suffered from the emergence of manufacturing centers in Germany, France, and America.

Who knows? Interdependence is a reality with contradictory twists. As consumers, both individuals and firms are strongly cosmopolitan and selfish. They buy what they want and take the best bargain. That's why more than 25 percent of America's car market and 60 percent of Britain's now consist of imports. The same impulse underlies the explosion of world oil consumption, which has tripled since 1960.

But the resulting global trading system rests on the mutual tolerance of states that remain highly nationalistic and do not share common political or cultural heritages. Economic growth has occurred much faster than political growth. Critical countries -- not just Saudi Arabia and Iran, but also South Korea and Brazil -- remain vulnerable to domestic disruption that affects everyone, not just themselves. And in industrial countries, the diversification of trade patterns has brought protectionist measures that depress global growth.

Some data from the United Nations give a crude picture of postwar economic growth. Especially in Europe, growth in developed countries already had slowed in the 1970s; average annual increases declined from about 4.9 percent to 3.4 percent. The developing countries -- in part buoyed by the rapid expansion of oil exports and the huge increase in international lending -- maintained about 5.5 percent growth in the 1960s and 1970s.

Now most forecasts see only 1 percent to 2 percent growth for the developed countries over the next few years. Predictions for developing countries are hazardous, but many may not get much more than the 2 percent to 3 percent they need to offset population increases.

The main question now is how long sluggish growth will continue and what political and social consequences it will have. Some essential changes -- the ability to grow with less oil -- may be easier than commonly suspected. Shifting drivers from larger to smaller cars and power stations from oil to coal takes time, but the effect is beginning to be felt. One recent British forecast is that demand for oil from the Organization of Petroleum Exporting Countires actually will fall by 5.5 million barrels daily (about one-sixth of the total) by 1990.

But other changes raise huge questions. The issue is put squarely here in Britain, where tough antiinflation policis are expected to increase the unemployment rate to about 8 percent next year from 5.5 percent in 1978. The arguement is that British firms need to streamline and become more productive; industries uncompetitive in world markets need to be replaced.

Economists talk about "adjustment," but adjustment usually means that someone has to start new businesses and that workers may have to move to new jobs. The government here has a religious faith that this will happen, but the recession will depress profits steeply. How quickly will new enterprise grow in that climate? It's difficult to avoid wondering whether somehow unemployment is slowly being spread around the globe.