British prime minister David Cameron has promised to lead a government for "one nation" after an election result that took everyone by surprise.  Not only did his conservative party win a second term, it now holds an outright majority. Mr Cameron says his decisive victory has given him a mandate for "tough" renegotiations over Britain's relationship with the European Union. Also in this edition of Between the Lines, is political speechmaking a dying art?  And what does one of Australia’s greatest speechwriters think about the impact of social media on our political discourse?