I watched the whole broadcast and was not really surprised as, apart from one other panel member who was excellent, they are all politicians. How long is it since you watched a politician that listened to other than his/her own voice?
The audience listened far better and did more to strip away the veneer than any of the other parties. Of the panel I thought that the American did the best possible job of acting in a civilised and suitably critical manner.
As for Straw, I think you have hit the nail squarely. He appeared more interested in his own origins than anything else. Pity he is so far removed from the public that even a comment on immigration from a black member of the audience was denied when it was put to him.