Is six-party politics here to stay? Is first-past-the-post a bulwark against extremism? What’s the value of a campaign promise in a coalition context? International broadcaster Nik Gowing chairs. Hennessy is Attlee Professor of Contemporary British History at Queen Mary’s; Scurr lectures in Politics at Cambridge; Wood is leader of Plaid Cymru; Boycott is Food Advisor to the Mayor of London.