youngmafbog - "Andy, public opinion is based on the thinking that it would be all dandy if we had not gone in. It may well have been, or it may not."
I disagree - I think public opinion is based on the very obvious truth that all that loss of life has done nothing to actually achieve any of the various, and always uncertain aims that were offered as the reason for going to war.
In no particular order -
WOMD - not found
Opiium Fields - growing nicely
Regime Change - chaos, bloodshed and puppet governments
Removal of terrorists - insignificant
Change of threat to the UK - increased .
So although as you rightly point out, we can only guess at the outcomes had we not gone to war, the outcomes from going stare us in the face on a daily basis.
"The majority of the public are either thick or too lazy to work anything else out for themselves so public opinion does not show whether is was worth it or not. Like I say we have no clue as to the outcome of inaction."
As you say, we do not know what inaction would have brought, only what action did.
As far as public opinion - I believe it is largely shaped by a media that increasingly gets its steer from its American counterparts - the constant scare-mongering that racks up tension and suspicion, but does sell papers.