Barack Obama managed to do the impossible yesterday: delight independents, commentators and his base (and even a few Republicans).He was invited to speak to a gathering of the Republican congressional caucus, and accepted. That's not unprecedented. What is, is that after a twenty-minute speech he took questions from his audience for an hour, whilst the camera rolled. Independent observers loved the unscripted, dramatic nature of the encounter, and the extraordinary fact that for most of the time the participants were courteously discussing actual policies, like grown-ups and everything. The Dem base was delighted because Obama, whilst civil, gave some of his questioners a pretty hard time. And just about everyone agreed that this was the president at his best - fluent, commanding, persuasive, charming, and the best-informed person in the room. Comments across the blogs and newspapers have been almost universally positive, almost giddy. Is this is what politics could be like?! We'll see - perhaps this will herald a real, enduring change of tone. Or perhaps it will be remembered as like the football match between British and German troops, before each tribe returned to their trenches and the guns resumed their fire.