When Ahmadou Ahidjo announced Nov. 4 that he was resigning the presidency here, the elaborate pageantry expected to surround the retirement of one of independent black Africa's founding fathers was notably absent.

But characteristically, the iron-willed Ahidjo, 58, the absolute political force in this affluent West African country for a generation, dropped the startling announcement and the unrevealing three-minute text that followed on his 8 million disbelieving countrymen during a live radio speech.

In a 20-minute ceremony two days later, Ahidjo formally handed presidential authority to his handpicked successor, former prime minister Paul Biya, 49. Ahidjo, who has ruled this uniquely prosperous nation since two years before independence in 1960, was then driven away from the presidential palace in the back seat of a black Mercedes without a backward glance.

Of Africa's founding fathers, Ahidjo's retirement is preceded only by that of former Senegalese president Leopold Senghor who handed over to his personally groomed successor, Abdou Diouf, at the end of 1980.

Kenya and Botswana experienced relatively smooth transitions when their founding fathers, Jomo Kenyatta and Sir Seretse Khama, respectively, died in office. There are still six founding fathers in power. Two of the eldest, Felix Houphouet-Boigny of the Ivory Coast and Hastings Banda of Malawi, have not allowed clear lines of succession to develop while maintaining firm grips on the reins of power.

The others also are getting on in age: Ahmed Sekou Toure of Guinea-Conakry, Julius Nyerere of Tanzania, Kenneth Kaunda of Zambia and Dawda Jawara of the Gambia side of the Senegambia confederation.

"Most statesmen believe in their immortality, but Ahidjo is one of the rare ones who is unimpressed with himself," said a senior diplomat, who insisted on anonymity. "To withdraw" from the exercise of unfettered power "in such a 'cold turkey' way is remarkable," the diplomat added.

Ahidjo, however, is spoken of by many Cameroonians as if he is still president. Many of the most cynical residents insist that the retired president will remain the manipulating eminence grise behind Biya.

Other Western diplomats and knowledgeable Cameroonians disagree. Unspecified but much speculated upon "ill health" precipitated Ahidjo's dramatic decision, said one diplomatic source, who added that Ahidjo had been trying to step down since 1979 "but no one believed" he was sincere.

In Cameroon, Ahidjo's autocratic style of one-party rule with a government-run, tightly controlled media, is unlikely to be altered anytime soon by Biya, although the two men are widely disparate in background and temperament, informed sources said.

Ahidjo, a Moslem from the rigidly stratified society of northern Cameroon, finished primary school and was trained as a telephone operator before entering politics in the 1940s. Biya, a Roman Catholic from the ascriptive groups of tropical southeast Cameroon, is a Sorbonne graduate with several university degrees, including political science and law. Ahidjo brought him into the executive office in 1962.

Biya takes control of Cameroon at a time when the country is experiencing a phenomenal 6 percent economic growth rate, a singularly high level in recession-plagued black Africa. Cameroon's exceptional affluence is universally attributed to Ahidjo's conservative fiscal policies, an early emphasis on agricultural development and the discovery of ever larger pools of offshore oil beginning in the mid-1970s.

The United States purchases 65 percent of Cameroon's oil exports, the lion's share of a 100,000 barrel-a-day production. Cameroon's growing production, expected to reach 125,000 barrels a day in three years, has raised its total annual petroleum revenues from $23 million in 1978 to $720 million in 1980 and to an estimated $1 billion today, according to a Western economist.

Cameroon's tightly run government is, in part, an outgrowth of first, a leftist insurgency that erupted in 1955 and, second, of the country's potpourri of 200 potentially antagonistic ethnic groups. The rebellion, which was backed with arms from China, was crushed in the early 1970s with the help of France, and an acceptable ethnic balance in government is maintained by bringing political leaders into the Cabinet from all the country's regions.

About 50 percent of the population follows traditional African religions while the remainder are Moslems and Christians. Cameroon's English-speaking minority, about one-fifth of the 8 million population, has been the major source of the government's critics but is largely mollified by being included in the country's significant economic progress. Both French and English are the official languages of Cameroon, a legacy of divided colonial rule between France and Britain.

While filling-out Ahidjo's unexpired term, Biya will not have to run for office until 1985. He is expected to be unopposed at that time.

Nonetheless, Cameroon's new president has been making moves to broaden his constituent base among the country's diverse population and come out from under the retired president's still-lingering shadow. In mid-November, Biya ordered an across-the-board 15 percent salary increase for all workers in public and private employment to match the country's oil-fueled 15 percent annual inflation rate.

Significantly, Biya refused to receive a delegation of his fellow Boulou people from Sangmelima after some of Cameroon's ubiquitous traders of the Bamileke ethnic group were threatened in the town by Boulous just several days after Biya took office.

"Rejection of a delegation from your home area is a very serious matter for an African leader," said a Cameroonian university professor, who declined to be identified. "By doing that, however, Biya showed that he was not going to play favorites and created the image of an evenhanded president with one gesture." Both he and diplomats said the Boulou of Sangmelima had openly expected special favors from Biya before the incident.

In keeping with his unassuming style, Biya drove himself to church the day after his Nov. 6 swearing-in. "After the services, he stopped outside as he usually did to chat with the other parishioners," the professor added. "Whenever Ahidjo moved in Yaounde everyone was ordered to stop."

Ahidjo's most extravagant legacy is a recently completed $380 million presidential office and residential palace complex built on Mt. Febe overlooking Yaounde. Biya has elected to continue living in his much simpler prime minister's house.

"People admire him for that also," added the professor. Map, no caption, By Richard Furno -- The Washington Post