What both men forget, or ignore, is that we live in an age of asymmetric media. The BBC reaches the most educated Americans, the full range of British newspapers from the Sun to the Guardian are now daily reading for Americans. Americans can gain the same understanding of British politics available to Britons and vice versa. The internet has fundamentally changed the way we communicate. So Blair's Question Time is news in the US as it happens. A US Congressional Committee's actions are reported in real time to the UK. Allegations in British newspapers are no longer reported second hand, but read and discussed daily. It takes no more effort to quote from the Guardian than the New York Times and live broadcasts of BBC4 are a browser away.
If the prewar WMD intelligence is shown to have been negligent or dishonest, asymmetric media will cause a few earthquakes in Canberra as well. It's well-known that both US and UK intelligence are leaking an avalanche at the expense of Bush and Blair. The one factor that the DailyKOS does not include is that I would guess the odd French or German intelligence document might well find its way to a backbencher or two in the house of commons.