At one o'clock on Sunday, amid the modern splendour of the St John's Wood synagogue and in front of a congregation peppered with politicians, diplomats and faith leaders – not to mention the Prince of Wales – Ephraim Mirvis will be formally installed as the 11th chief rabbi of the United Hebrew Congregations of the UK and the Commonwealth.
Despite representing neither Britain's ultra-Orthodox nor its Progressive Jews, the office has been described by the outgoing chief rabbi, Lord Sacks, as "one of the great positions of rabbinic leadership in the Jewish world, one of the most respected, one of the most influential, as well as one of the most challenging".
Few would disagree with Sacks, who gives way to Mirvis after 22 years in the job. During that time, Sacks undoubtedly proved himself a respected and influential figure. But all too frequently he also found himself challenged.
For all his academic rigour, thoughtful arguments and elegant rhetoric, Mirvis's predecessor was a divisive chief rabbi: a leader often accused of putting the needs and demands of the Orthodox right before those of liberal and Reform Jews.
"One of Sacks's great strengths was communicating with the outside world and he had an enormously high profile on Thought for the Day and in the House of Lords," says Jonathan Romain, head of the Maidenhead Reform synagogue. "But he wasn't very successful inside the Jewish community. He often talked about pluralism outside of Judaism, but never acknowledged it within."
That view is shared by Meir Persoff, author of Another Way, Another Time: Religious Inclusivism and the Sacks Chief Rabbinate. Although he describes Sacks as "the outstanding theologian of his time in England", Persoff believes he spent too much time acting as a spokesman and not enough as a proper mediator. "He said one thing to one group of people to the right of the community and then said other things to the left of the community," says Persoff. "He got himself in a lot of trouble."
He offers a possible explanation for Sacks's occasional tendency to speak "with a forked tongue" and to veer towards the right: "Because he wasn't essentially trained in the yeshiva, where many of the Orthodox rabbis are trained, he tended to look over his shoulder continually towards the right of the community – towards the ultra-Orthodox – so as not to upset them in what he did."
Lord Sacks has addressed some of the lingering criticisms of his leadership in recent farewell interviews. Asked by the Jewish News whether he spent too much time away from the people he represented, he replied: "Ninety-five to ninety-eight per cent of my time is spent with the Jewish community. I do Thought for the Day which takes little time and people say, 'Oh, he's spending all his time on the outside world'." He also said that "the turbulence" with non-Orthodox movements had actually served to bring the differing parties closer together for mutually respectful work and dialogue.
Mirvis is viewed as more of a pastoral figure. Born in South Africa in 1956, he served as chief rabbi of Ireland from 1985 until 1992 and went on to become a senior rabbi at the large and successful Finchley United synagogue.
Those stints, according to Keith Kahn-Harris, co-author of Turbulent Times: the British Jewish Community Today, could be key to Mirvis's time as chief rabbi and could help him bring together Britain's pluralistic and polarised Jewish community.
"What he does have – which Sacks really didn't – is significant synagogue experience in what is one of the most vibrant Orthodox synagogues in the UK," says Kahn-Harris. "He's very much someone who's worked in the trenches, but that doesn't mean he doesn't have an intellectual background or intellectual heft, but he doesn't have it in the same way that Sacks did."
Persoff agrees: "Rabbi Mirvis is not a philosopher; he's not an orator of the standing of Lord Sacks but he has an understanding of the community from the inside; he knows its needs and its requirements and I think that given the fact that there were very few people of outstanding qualities to choose from, he was probably the ideal person to take the job within the ranks of the United Synagogue."
It is hard to predict how much freedom Mirvis will enjoy in his new job. Persoff argues that for 70 years, successive chief rabbis have found themselves constrained by the dayanim – judges of the court of the chief rabbi.
"They set the tone and the line that the United Synagogue have to follow," he says. "And if one of the chief rabbis falls out of line, he is rapped over the knuckles by the dayanim. Whether or not Rabbi Mirvis will be able to stand up to the line that the dayanim are going to set remains to be seen."
But notwithstanding the internal and external pressures – nor the continuing debate over how much relevance and influence the role of chief rabbi possesses among the diverse Jewish community of 21st-century Britain – Mirvis's appointment has been greeted with an optimism that is guarded in some quarters, but effusive in others.
"Rabbi Mirvis is currently an unknown quantity to Liberal Judaism," says Rabbi Danny Rich, the chief executive of Liberal Judaism. "[But] I wish him well in a demanding post. National responsibilities do not make for light work or easy relaxation."
As far as Kahn-Harris is concerned, the new chief rabbi is wise to retain that unknown-quantity status. When Sacks was installed in 1991, he says, he faced high expectations and loud calls for a decade of renewal. "I don't think people will have the same expectations of Mirvis and I don't think he'll start with a bang in the same way," he says. "I think that's probably the right approach."
Rabbi Laura Janner-Klausner, chief rabbi for the Reform movement, feels that people are beginning to realise that the era of "one-community-one-voice" is over and that the British Jewish community needs to find new ways to deal with its inherent diversity and to support the rapidly growing ultra-orthodox Haredi population.
But she remains excited about the new chief rabbi – whatever his plans and priorities. "We don't know what he'll do. Luckily, he's a fabulous chap who is multi-skilled, so we'll see where he goes. I always think that when people say, 'Oh, Rabbi Mirvis will be a rabbi's rabbi and he'll be good for the community', it already clips his wings. And I don't want to clip his wings."