It is 1.15am and a dozen students are sitting in an upstairs bar at Warwick University. The chill weather had frosted the cars outside hours before.

But rather than bottles of Bud or vodka and cranberries, they are armed with a sheet of passages from Maimonides, about to begin the latest of late-night sessions at Limmud’s annual winter conference.

The thunder of beats from Jerusalem band Coolooloosh, performing elsewhere on campus, had just died down when the dedicated circle take up their texts, led by Rabbi Gideon Sylvester, who runs activities for the United Synagogue’s young people’s department, Tribe, in Israel.

His topic is “one that has troubled me for many years — the ethics of outreach. Is there a religious imperative to spread the word and make people religious?” And if so, “should I use every technique in my power to do so or are there ethical limitations to that?”

Though it’s 2.30am by the time he hands over to the next presenter, in the downstairs bar hundreds of youngsters are still up, singing and dancing round some frenetic tabla drums.

British Jewry’s annual five-day festival of learning, which ended last Thursday, is “one of the most vibrant things in the Jewish world”, observed Gregg Drinkwater. He is executive director of the Denver-based Jewish Mosaic, which advises American Jewish organisations on lesbian, gay and transgender issues.

Which is ironic, he added, because British Jewry’s official structure, with a Chief Rabbinate and other centralised institutions, seemed “a roadblock to vibrancy and transformation”.

Mr Drinkwater took part in one of the most talked-about sessions, an exchange with Rabbi Shlomo Riskin, the Chief Rabbi of Efrat, who made, Mr Drinkwater said, “the most inclusive statement towards gay people I’ve ever heard from an Orthodox rabbi in a public forum”.

Rabbi Riskin said there was no halachic bar on gay couples adopting children and it was better for gay people to live in a loving relationship with a partner than be promiscuously single.

While around 170 young Limmudnik teens produced a newspaper or learned to draw hamsot (good luck symbols) in their own programme, adults could choose from up to 30 classes every two hours.

Guest presenters worked hard. Melvin Konner, an anthropologist whose work is admired by the Chief Rabbi, was by no means untypical in delivering five 70-minute lectures in little more than 24 hours. He once summed up Jewish history in six words: “Israel strength, diaspora weakness, Israel strength.”

But just as Jewish interpretation, according to one presenter, is as much about the white spaces between the black letters, so Limmud is as much about what happens between scheduled sessions. Like the young woman in the corridor who told Tamar Ross, professor of Jewish thought from Bar-Ilan University: “You are the reason I held on to my Orthodoxy.”

While the growing number of visitors from abroad — Romania, Canada, South Africa — testified to the influence of probably British Jewry’s most successful export, its brand remains strong at home. Organisers noted this year a rise in the number of participants from Manchester, where a day Limmud is planned for May.

“We’re getting an increase in volunteers coming forward to put an event together,” said David Hoffman, co-chair of the Manchester event and also co-chair of this summer’s LimmudFest.

Limmud’s open platform means that almost anyone can come to present a session. So it was that Deborah Fink, a founder of Jews for Boycotting Israeli Goods, performed an anti-Israel satirical cabaret to an audience of 30 one evening, some of whom applauded, while others sat in bemused silence.

Hundreds more, however, came for Limmud’s version of Strictly Come Dancing — won by Nikki Milan, wife of the conference’s caterer.