IMAGINE that the United Kingdom was an absolute monarchy known as Windsor Britain. Imagine that Prince Charles, heir to the British throne, had dozens of brothers, scores of sons and hundreds of cousins, and that the broader House of Windsor numbered thousands of lesser princes and princesses. Imagine further that all these royals pocketed fat state stipends, with many holding lifelong fiefs as government ministers, department heads, regimental commanders or provincial governors, with no parliament to hold them in check. Now imagine how sporting these princely chaps would be when the throne fell vacant, if the only written rule was a vague stipulation that the next in line should be the “best qualified” among all the Windsor princes.

This is roughly how things look in Saudi Arabia, a family enterprise run the old-fashioned way. Here the king is not only prime minister. He also appoints the members of parliament and designates a successor to the throne. Yet the actual workings of this system are not so simple. The size of the ruling al-Saud family (at least 5,000 hold princely rank), and the accumulated privileges of its leading princes are such that kings must take care to balance rival interests. They must also accommodate Wahhabist clerics who expect rewards for sanctioning absolute monarchy, technocrats who actually manage the country and even, sometimes, those of their subjects who grow restive, and demand a voice beyond presenting personal petitions at royal receptions.

In a smaller country this all might be dismissed as quaintly droll. But the Saudi kingdom has nearly 30m people, sits on 20% of global oil reserves, houses the holiest sites in Islam and is situated in a particularly turbulent region. At a delicate time for the world economy, and an equally delicate juncture for regional affairs, the choices that the immensely rich kingdom makes are especially relevant. And just now it happens to be on the cusp of changes in leadership that may prove as wrenching as any in its history. Not only its king but many of its powerful princes have grown old and must soon be gone.

This need not cause alarm. Saudi Arabia is, by many measures, doing rather well. Its $420 billion economy faces little risk of losing its place as the biggest in the Middle East, given steady oil reserves and production, around $150 billion in annual energy exports and a strengthening world oil market. The country's net foreign reserves still nearly equal its GDP. Economists expect growth to accelerate slowly from around 4% this year, ensuring steadily rising living standards.

The country has also withstood political risks rather well. Its large pool of idle youths, with their liking for the fierier brands of Islam, have made the kingdom a wellspring of extremism, most famously producing Osama bin Laden and three-quarters of the September 11th 2001 hijackers. But a mixture of popular disgust and concerted policing appears to have taken the romance out of violent radicalism.

Saudi Arabia remains shockingly conservative—indeed, suffocatingly oppressive to its women. Yet the trend has been towards a gradual loosening of strictures and opening of minds. In the past five years alone, new government programmes have sent close to 200,000 Saudi students overseas, more than were sent in the previous 20 years.

King Abdullah deserves much credit for the general lightening of tone. Gruff, homely and popular, he has ruled since 2005. He spent 23 years as crown prince before ascending the throne, ten of those as an unofficial regent after his predecessor, King Fahd, suffered a debilitating stroke in 1995. Holidaying in Morocco this month after a North American jaunt, Abdullah shows no particular sign of frailty. His youngest son is just seven years old. Yet the king is now thought to be 86. His windows of lucidity are shrinking; loyal minders frequently rephrase his words so they make sense. When he abruptly postponed a planned French leg of his current summer tour, rumours about his health abounded.

Unfortunately, Abdullah's quiet promotion of social reform has not been matched by any similar move towards political change. Royal rule remains as absolute as ever, meaning just as inefficient and just as unpredictable. Although there is a sketchy script for the next act, neither actors nor audience look very inspired.

The king's half-brother, Crown Prince Sultan (seen above to the left of the king), has been defence minister since 1962 and next in line to Abdullah since his full brother, King Fahd, appointed him second deputy prime minister (a post traditionally held by the crown-prince-in-waiting) in the 1980s. But Sultan is reckoned to be just a year younger than the king, and his health is poor. He spent most of last year secluded at his vast estate in Morocco, convalescing from a serious but unnamed disease. His return to Saudi Arabia in December, and apparent resumption of duties, prompted surprise. In his rare public appearances, the crown prince looks frail and distracted.

Prince Nayef, one of Sultan's full brothers, has been seen as the likely next in line to Sultan since the king promoted him last year to the crown-prince-in-waiting post. Nayef is only 77, and fairly spry. But he seldom travels outside the country. As a crustily conservative minister of the interior for the past 35 years he has not endeared himself to Saudi reformers and professionals. Since his appointment last year he has worked to soften his image, but the choice still rankles with the many Saudis, including some senior princes, who would have preferred a more modernising figure.

Most Saudis expect that their ruling family will, as it usually has, reach quiet consensus on whom to crown, assuming that King Abdullah and Prince Sultan depart in reasonably short order. Aside from the 1992 royal decree tipping the “best qualified” prince to rule (a term that in Arabic can mean either the most virtuous or the most capable), there are some established guidelines. Traditions of Muslim kingship suggest that the line should pass through brothers of one generation in order of age, before descending to the next.

Yet with their unique political system looking increasingly anomalous in the modern world, Saudis are beginning to worry about what might follow if the al-Sauds fail to agree. This has happened before. Although Saudi Arabia became a kingdom only in 1932, the al-Saud family has controlled parts of this territory for 266 years. Twice in the 19th century, the Saudi emirate collapsed owing to struggles between brothers and cousins over who should rule. Weakened by such troubles, the emirate was completely overrun by a rival clan, the al-Rashids, in the 1890s. It was resurrected through the daring of Abdel Aziz, who rallied local tribes and captured his future capital, Riyadh, in 1902.

The spectacular success of Abdel Aziz—who went on to conquer much of Arabia, ally himself by marriage to its biggest tribes and found the modern kingdom—allowed him to disqualify all other branches of the al-Sauds from rule. Henceforth the line of succession would run only through his sons and their descendants. Even so, when he died in 1953 leaving more than 30 living sons, the two eldest ones, each backed by a powerful faction, bickered dangerously over the leadership until the eventual triumph of Faisal in 1964.

Sudairi empowerment

In overthrowing Saud, his impulsive, spendthrift older sibling, the more capable Faisal relied heavily on support from the Sudairis, the largest group of Abdul Aziz's sons born to the same mother. A non-Sudairi himself, Faisal made sure the seven Sudairi brothers were well rewarded.

The eldest, Fahd, who served as interior minister before he himself became king in 1982, put his son, Prince Muhammad, in charge of the Eastern Province, the main oil-producing region. Sultan took the lucrative defence portfolio, and Nayef eventually succeeded Fahd at the interior ministry. Both Sultan and Nayef also appointed one of their younger Sudairi brothers, as well as one of their own sons, as deputies. Another of Sultan's sons, Prince Bandar, served for two decades as Saudi ambassador in Washington until he was appointed head of the Saudi National Security Council in 2005 (he now seems to have fallen into disfavour). Prince Salman, also a Sudairi brother, has been governor of Riyadh, since 1962. He is seen as an important arbiter and disciplinarian within the family.

The empowerment of the Sudairis brought continuity to the system, preventing the recurrence of open squabbling. It also prompted other princes to align quietly against them. Before becoming king, Abdullah struggled to preserve an independent power base through his command of the National Guard, a large, paramilitary force drawn largely from desert tribes. He cultivated allies among his other brothers and with Faisal's powerful sons, particularly Prince Saud, who has been foreign minister since 1975, and Saud's brother, Prince Khaled, whom the king recently named governor of Mecca.

Saudi-watchers suspected that the subtle aim behind such manoeuvres was to ensure that when Sultan eventually became king, he would not be strong enough to complete the Sudairis' dominance by keeping the line of succession within their branch. Four years ago the king suddenly created a new family council, the Allegiance Commission, that some analysts saw as part of this balancing game. The 35-man body represents the sons of Abdel Aziz: 16 are surviving brothers of the first generation; the remaining 19 are grandsons of Abdel Aziz, each one representing the family of one of his deceased sons. The council's chair, Prince Mishal, a senior non-Sudairi, is a close confidant of the king. Despite filling a fifth of the council's seats, the Sudairi faction's weight inside it is unequal to its power within the state.

The council has the job of selecting the crown prince—after Sultan becomes king. This suggests that Sultan, unlike previous rulers, will be legally bound to give way on this crucial point to the wider family's wishes. The council also has the right to remove sitting kings on health grounds. This reflects a hard lesson learned by Abdullah when he was crown prince: the Sudairis, along with the king's retinue, for years frustrated his efforts to take control, despite the obviously impaired capacity of King Fahd who was often barely conscious when wheeled out for state occasions.

Clever and “modernising” as the creation of the family council may have been, it has yet to prove its efficacy. And last year's elevation of Nayef to the crown-prince-in-waiting job was seen as a contradictory move by the king, pre-empting the body he himself had recently created. Prince Talal, an outspoken senior non-Sudairi, openly questioned the appointment. Some people reckoned that since Sultan's poor health may make him unlikely to outlive Abdullah, the king was persuaded to anoint another Sudairi in the interests of family peace. Wilder talk suggested that it was not ill health but rumours of the alleged insubordination of his son, Bandar, that seemed to threaten Sultan's accession.

Grandsons in waiting

Saudi royalists dismiss whispers of factional tensions and scheming as absurd, and it is true that the al-Sauds, helped by their direct or indirect control of much of the Arab media, are adept at keeping their squabbles private. Yet the dispensation that has guided the kingdom for the past five decades has weakened. Several senior figures in the Saudi establishment are ailing, including the foreign minister. And in recent weeks, the long-serving princes who headed the Saudi navy and air force were replaced by professional soldiers. Some saw this as a sign of the waning influence of Sultan within the armed forces.

When or whether the throne will pass to the second generation of Abdul Aziz's heirs remains an open question. Although most of the patriarch's surviving sons do not seem to want the job, there are, Sultan and Nayef apart, at least a couple who might: Nayef's 73-year-old full brother, Salman, the governor of Riyadh; and Prince Muqrin, aged 64, a former fighter pilot who is now head of intelligence. Among the grandsons the choice is of course much wider. The leading contenders include two Muhammads: the son of Nayef who is an effective deputy minister of interior; and the son of Fahd, who still governs the Eastern Province.

Understandably, a growing number of Saudis resent having no say in such matters. On internet chat sites, in private salons and in the occasional open petition, they call not for the overthrow of the al-Sauds, but only for the transformation of the kingdom into a constitutional monarchy. The call comes from across the spectrum, from hard-core fundamentalists to Western-educated liberals. But so long as Saudi kings have their hands on the tap controlling the miraculous oil wealth, that looks highly unlikely.