"Why you would ever imagine that the whole lot might make up a false history while ordinary folk like us knew the truth.
You would find the same stance in other knowledge areas like science laughable."
You should perhaps apply some of that logic to your own hard wired prejdices Keith.
Is half of the research you speak of is based on letters written by soldiers at the time, have you EVER given a moment's consideration to the message a soldier would want his family to read.
Do you really believe he'd tell of the misery and hardship of the trenches, or might he say he's fine and giving the "Hun" a good hiding?
As for diaries, the men would know that trouble would follow any utterances considered seditious by their superiors. They'd hardly say what they Really thought about being sent over the top into the German machine guns, or what they thought of those who sent them.