When Jonathan Sacks was appointed Chief Rabbi in 1989, he was so firm a favourite, it would have been astonishing had he not got the job. Not only was he widely viewed as the heir-apparent to Lord Jakobovits, but he also had a powerful patron in Lord Kalms, who was chairman of Jews' College when Rabbi Sacks was its principal (though the good lord subsequently lost faith in his protégé).
This time, the situation could hardly be more different. There may be some credible candidates but there are no front-runners and no Kalms figure championing anyone's cause - no prince, no kingmaker. In that sense, Lord Sacks leaves a vacuum rather than a vacancy. But there is still plenty of time for contenders publicly to establish their claims.
Had Lord Sacks decided to stay on, emulating his predecessor, who retired at 70, there would have been little to stop him. But it had widely been anticipated that he would step down in 2013, having reached 65 in March of that year. Retirement will leave him free to lecture and write without the strains of communal office. His international reputation has never been higher and it will be no surprise if he finds a prestigious academic post abroad.
But the one thing he will be glad to escape is denominational politics and the risk of religious strife. He has never liked being the centre of conflict and - unlike Lord Jakobovits, who variously went into battle against West Bank settlement or the excesses of the welfare state - he has tried to keep his distance from controversy. Barring some eruption in the next couple of years, he will leave the community a less fractious place than might have been predicted a decade ago.
In part, this is because the Charedi establishment seems to have called a truce on attacks on the Chief Rabbinate. Twice during Lord Sacks's tenure, interventions from the right could have brought about his resignation; once over his appearance at a (secular) memorial event for the Reform leader Rabbi Hugo Gryn; then over his "heretical" book, The Dignity of Difference, which he was forced to revise.
But cooler heads must have calculated that ousting the country's (perhaps the world's) most articulate spokesman for Orthodoxy - "the acceptable face of fundamentalism", as Sacks once referred to himself - would eventually have proved counterproductive.
In the meantime, after the debacle over Rabbi Gryn, Lord Sacks was able to rebuild relations with the Progressives. He made the concession of agreeing to non-Orthodox presidents of the Council of Christians and Jews - a move which Lord Jakobovits had resisted as a challenge to the primacy of Orthodoxy.
He has managed to avoid further clashes with the non-Orthodox largely by not writing or saying anything which could have upset them. Indeed, they could happily endorse much of his recent work on social responsibility - a sort of Orthodox version of tikkun olam.
It is significant that last year's Supreme Court ruling on Jewish school admissions did not trigger some new outbreak of religious infighting of the kind that disfigured the Chief Rabbi's earlier years. The court case, of course, started with his refusal to recognise the Jewish status of the child of a non-Orthodox convert. But the Chief Rabbi has emerged largely unscathed from the affair and the differences between Orthodox and non-Orthodox have, compared with previous years, been temperately expressed.
Whoever takes the reins from Lord Sacks will probably be expected to maintain the delicate balancing act in the United Synagogue's relations with the religious left and right. His successor's every move will be closely watched for any shift.
Lord Sacks, while he gave Limmud his blessing, has conspicuously not visited the conference during his office, mainly to avoid a public show of difference with his Beth Din or, more particularly, its erstwhile head Dayan Ehrentreu, who disapproved of it. If his successor maintains the same policy, he will immediately stamp himself as "of the right".
Then there is unfinished business over women. United Synagogue lay leaders wanted to clear the way for women to become trustee-officers of the organisation or chairmen of local synagogues (they can only be vice-chairmen at present).
This would nudge the United Synagogue closer in the direction of modern Orthodoxy. However, they have been clearly unable to persuade the Beth Din. The Chief Rabbi, opting for a quiet life, has chosen not to ally himself with the moves for reform, happy to leave the issue to his successor.
Picking Chief Rabbis in the past has largely been up to lay leaders. It will be interesting this time to see what input there is from United Synagogue rabbis and their regional colleagues. There is a body of opinion that believes the next Chief should be a "rabbi's rabbi" - more a captain of the clerical platoon than an envoy to the outside world or globetrotting intellectual.