The annual White House Correspondents’ Association Dinner returns this Saturday for a night of comedy ‘roasting’ – where the great and the good are ruthlessly mocked in celebration of the freedom of the press. In recent years, however, the night has taken on a different tone, with the atmosphere of warm self-deprecation and bipartisan bonhomie replaced by something more scathing and serious. This week Jonathan Freedland is joined by Jeff Nussbaum, a former senior speech writer to Joe Biden, to discuss the art of writing gags for presidents and whether there is still space for humour in US politics.