Three weeks ago, the Campaign Against Antisemitism did not exist. Three months from now, it might no longer.

As a pop-up campaign, it might just as easily pop down. In the new, social media-driven, grass-roots-organised world, success and failure are no longer measured by longevity and standing but by immediate impact.

Its swiftly organised rally on Sunday drew an estimated 4,500 people — including the Chief Rabbi and the President of the Board of Deputies. And that is the real point.

The rally is a physical manifestation of a change that could, sooner rather than later, render simply irrelevant the established bodies and methods of our community leadership.

In recent weeks, we have reported the widespread dissatisfaction with the response to rising antisemitism by the Board and the Jewish Leadership Council. In earlier times, that dissatisfaction might have produced a lot of moaning, some angry letters to the JC and nothing else.

But in a world where Facebook and Twitter can link millions in minutes, the like-minded can now organise new campaigns overnight. Which is how a group of previously unheralded grass-roots activists put together the biggest communal rally of the year. And how they secured the presence of the Chief Rabbi and the President of the Board.

Both have been criticised for doing too little — and were effectively dragged into attending by the sheer energy of the organisers. But however undignified the booing of Vivian Wineman and Laura Marks might have been, the Board should not simply dismiss it as unworthy.

Because it demonstrates a real feeling of anger that the representative body of British Jews is simply not doing that basic job — representing British Jews.

The sensible response would be take a long look at itself and work out how it can adapt to the demands of the 21st century.