Recent polling data and election results paint a picture of woe for Britain's two main political parties. Of course both Labour and the Conservatives have suffered periods of decline throughout their history. But arguably never before have both parties been so riven by internal divides and suffered such a loss of public confidence at the same time. Edward Stourton looks to historical precedents for guidance on today's political turmoil and asks if the two parties' decline is now terminal. With Tim Bale of Queen Mary University of London; Lord Lexden, official historian of the Conservative Party; Deborah Mattinson of Britain Thinks; Charlotte Lydia Riley of the University of Southampton; John Sergeant, former BBC Chief Political Correspondent; and Adrian Wooldrige, author of the "Bagehot" column at The Economist.