Jim,
You have put up just a few words of what she said

Yes, and it is unequivocal.
They do not contradict themselves elsewhere. How could they?

Pennell, "myths have built up that suggest ordinary British and Irish people backed the war because they were deluded, brainwashed and naïvely duped into supporting the conflict. My research shows that this was simply not the case."

Margaret Macmillan said, "Britain certainly thought it had legitimate reasons for going in, and I think it did," she says. "

Quite unequivocal Jim.
They reject your view completely, and you will find not one single historian who challenges either of them.