Jingoist and extremely dishonest bullshit – an insult to those who died.
It was strictly against the rules for an ordinary soldier to keep a diary
All correspondence home was strictly censored, dissention in the ranks was severely punished; often those found guilty of such were placed in the most dangerous positions, which virtually amounted to being executed
Desertion, and sometimes, slowness to 'go over the top' was routinely a capital offence
The only reports to come from the front were the official diaries (below), which did not even record the names of the 'ordinary' soldiers.
http://www.greatwar.co.uk/research/military-records/british-army-war-diary.htm
By 1916 Lord Derby's recruitment drive was announced to have failed and was abandoned in favour of compulsory enlistment.
Enthusiasm for the war was a myth circulated by "officers, toffs and their toadies" according to the Liverpudlian docker who had lied about his age to enlist "we usually shouted the toadies down when they were given the job of egging us on".
He said the lies about the army being "a man's life" had been "kicked into touch before we even embarked for Europe".
He and most of his mates had enlisted because "there was no work back home".
He described the experience as "traumatising and brutalising" – he refused to speak about it for years; many of his comrades "couldn't settle back into civilian life and the only work on offer was to re-enlist and go off and fight in Ireland with the 'Tans'.
Desertion, which usually involved "walking away from the noise", was automatically met with the firing squad.
We were told that, if a push was on, "those condemned to death were taken out and put in the front line" – if they survived they were re-imprisoned and later shot"
We were instructed to "tell anybody who said there was any honour or glory in fighting in that filthy war, that they are fucking liars – it amounted to nothing more "
"Don't shoot me, I'm only the messenger" as somebody here is fond of saying.
Jim Carroll

WW1 British Army War Diaries
British Army War Diaries were handwritten or typed documents providing a daily account of the activities of a British, Dominion, Indian and Colonial Army unit on active service. This was a British Army Field Service Regulation dating from 1907. Sometimes the War Diary was designated as an Intelligence Summary.
It was the responsibility of the commander of every military unit – from the level of a battalion to a division – to ensure that the War Diary was kept up to date. It was to be written up each evening by a specific junior officer and usually signed off by a senior officer or the commanding officer.
The War Diary was compiled by month for every month that the unit was on active service.
In addition to the completed official War Diary Army Form, there might also be sketches, messages, maps and Operational Orders included as appendices.

http://www.dailymail.co.uk/news/article-2491760/Harry-Drinkwaters-lost-diary-Great-War.html