For 15 years, Intelligence Squared has vigorously championed the spoken word. The finest speakers from across the globe have come to our stage — to argue, to move, to persuade and change minds. Their speeches epitomise the vital role that public speaking plays in our lives. To celebrate the power of oratory, we held a major event which will showcase how great speeches have swayed the course of history and demonstrate how, more than ever, we need them to help define our values and who we are.

Barack Obama’s director of speechwriting, Cody Keenan, shared his experience of helping craft the presidential speeches that moved the hearts and minds of millions around the world. Alongside him was be Philip Collins, Tony Blair’s former speechwriter and Times columnist, whose new book argues for the importance of speeches in protecting and promoting democracy. With Newsnight’s Emily Maitlis in the chair, Keenan and Collins unpacked the tricks and techniques that have been used by the most brilliant orators down the centuries and which are still working their magic today. Bringing this all to life were star actors Carey Mulligan, Jeremy Irons, Jade Anouka and Simon Russell Beale, who will perform extracts from remarkable speeches – some familiar, others that will surprise – from different continents and eras.

What is it about a great speech that can give voice to people’s intense but unarticulated feelings? What is that special alchemy of words and personal charisma that makes us as susceptible to dangerous demagogues as to the morally uplifting oratory of a Mandela, a Martin Luther King or a JFK?