Leadership, the economy and faith in times of crisis were among topics discussed by Gordon Brown and the Chief Rabbi before the 250 guests at a Hendon Synagogue gala dinner.
The former prime minister was participating in the inaugural Hardman Conversation, in memory of the community's long-time minister, Reverend Leslie Hardman. The event also marked the official opening of the synagogue's Hardman wing.
Questioned by historian Sir Martin Gilbert, Mr Brown stressed the dangers of protectionism. The challenges of the day, from financial security to climate change, were global problems that could not be solved by any one government.
"The answers lie in international co-operation," he said. "Unless we do it together, financial security will not be on the agenda for some time."
His faith had helped him through difficult times. "You need a compass for every single major event."
Although there had been "many crises to choose from", Mr Brown's lowest point had been the banking collapse of 2008. It had taught him the importance of having a system based on the fundamental ethics of fairness and responsibility. "You must have rights and responsibilities side by side," he explained.
Discussing developments in communications technology, Lord Sacks saw the positives in "every democratisation of access to information" for opening up power and making it more difficult to maintain hierarchies.
"Just as printing destabilised Europe, you have a period of destabilisation but in the long term there is a benefit and gradually there is the spread of freedom," he said.
Mr Brown added: "The conversation between elites will never be the same again - the people will always be involved. They can connect across borders and therefore repressors can't last forever. The truth will get out in ways that it could not have done 50 or 100 years ago."
Lord Sacks also said that British Jewry "could not have a better friend" than Mr Brown.
The event raised £20,000, the proceeds incorporating a raffle with prizes including a diamond necklace and helicopter lessons.
Synagogue chair Marc Mayer said "the main idea was to show the community that we could do something bigger.
"We want it to become a regular fixture in the calendar - and tonight set the bar quite high."