If there is one thing on which the 22 nations gathered here for two days of summitry agree, it is that there will be no Cancun II, no Sons of Cancun, no repetition of this unprecedented meeting of nations whose only common denominator is that they were invited and agreed to come.

As the British foreign secretary, Lord Carrington, remarked at the conference's start, it might make the rest of the world "suspicious" if these 22 nations were to meet again behind closed doors, presuming to speak for the rest of the 130 or more members of the world community.

At the same time, spokesmen from country after country have warned against expectations that something substantive might emerge. No one has claimed that anything did.

But from its initial planning stages last year, the Cancun summit was billed as an international "happening," the mere existence and uniqueness of which might be enough to break through two decades of global disagreements, mistrust and recriminations over how the world's wealth should be divided.

The idea for a North-South summit came last year in a report from the Brandt Commission, a private group of prominent international figures established in the late 1970s to study problems of the world economic system and the needs of developing countries.

The report, released in February 1980, called for a summit limited to 25 nations from the industrialized and developing worlds, at which leaders could get together and "thrash out" their problems with a "candor and boldness" that could "change the international climate."

Although there has been little evidence here of thrashing, there is hope that the "spirit" of Cancun will spill over into the international tangle of lower-level institutions where the minutiae of world finance and development are debated year-round, and where the climate of debate long ago turned frigid.

The battle lines between North and South were first drawn before the ranks of the "developing" world were filled with the mass decolonizations of the early l960s.

In l955, 29 nations, led by Egypt, Indonesia, India and Yugoslavia, joined in the nonaligned movement, a Third World bloc to resist the superpowers of East and West.

By l964, the Third World had decided its problems lay primarily in the international economic structure, where it sold cheap and bought and borrowed dear. That year, 77 developing countries in the United Nations put forth a joint position for the first U.N. Conference on International Trade and Development.

Since then, the "group of 77" -- now 120 countries -- has led the fight for what has become known, from the wording of a 1974 U.N. resolution, as the New International Economic Order. Most industrialized nations, including the United States, opposed that resolution.

In the l970s the increasingly acrimonious debates centered on several issues. The North attempted to block change. The South insisted on a reordering of the world's financial structures that would give it increased access to development capital, increased control over prices of its exports and imports, help in increasing its own production and emergency aid to the poorest.

The South demanded "global negotiations," a full debate of the issues in the General Assembly, where it held a majority. The North insisted that the talks take place in the specialized agencies, the smaller units of the world community where the North wields more power.

When then-World Bank president Robert S. McNamara asked former West German chancellor Willy Brandt to form a commission to study the question, an impasse had been reached.

While the issue of global negotiations languished in the United Nations, the Brandt Commission's call for a world summit was quickly seized by a number of countries.

Lists were drawn up for invitations. Then-president Carter was one of the first to refuse, on grounds that it would be merely one more forum for the Third World to criticize the United States. The Soviets refused, charging that world economic problems were the result of Western imperialism.

Ronald Reagan, whose Third World policies had been denounced by many attending the conference here, surprised the organizers by agreeing to attend.

Delegations from both ends of the globe have pointed out here, meanwhile, that while talks on global negotiations have been stalemated the world economy has gotten worse for everyone.