You say it like Blair, Campbell and Mandelson one day decided to just go to war all by themselves. Dismissing that it would have had to go through cabinet as plainly it went to vote in the HoC (which was not required by the way) and anyone who disagreed would have had to have walked, like Robin Cook did. So something that went through the cabinet and through the house is sofa government? Nah, not having it.
Yes there were mistakes but you are painting it from a very anti-Blair bias. Which almost all of old labour supporters do. It was a difficult choice and hindsight proved it was wrong but we don't live by hindsight and if we did nothing and a nuclear or chemical device found its way onto the streets of London that originated from Iraq, people would have a very different opinion to the pacifist ones now seen.
As for newspapers, the best way to respond to bad press is by trying to control what gets out there in the first place. Nothing wrong with that, very sensible. But you can't control all the press and things do get out there and you have to be on top of that as a government. But it wasn't just newspapers it was 24 hour news TV, things that people may not have seen for days afterwards suddenly are being beamed live in minutes. People want a reaction from them immediately afterwards.
It absolutely wasn’t a difficult choice - a first year undergraduate could have told him that Saddam wouldn’t work with al-Qaeda, and as for the alternate reasons that were given people at the time told him Saddam would not use whatever chemical weapons he had except in the direst of circumstances, and the idea he wanted to get nukes was disproved even before the story came out.
It also would not have required Bond at his peak to discover that the US administration wanted to get rid of Saddam irrespective of any actual need to do so.
As for this “yes, but what if a nuke / chemical weapon got onto the streets of London” rubbish, that was never a sensible argument even then. Chemical weapons especially were in loads of objectionable people’s hands, and they do not require a regime thousands of miles away to give the green light to be used. The Tokyo attacks proved that even nerve gas was within the reach of a committed group, never mind less sophisticated stuff - all that was needed was luck, a bit of skill and the commitment.
His decision was made solely because he wanted to stick close to the Yanks. He would have been better off telling Bush to sack the people who were driving them and us into what was the defining disaster of our times (hopefully).