Military tribunals quizzed people about their tea-drinking habits in a bid to send them to fight in the First World War, a new exhibition has revealed.

While many would view tea as a cornerstone of British culture, admitting to drinking it was deemed by tribunals to be a sign of hypocrisy and cowardice if a person was a conscientious objector.

It appeared that the tribunals tried to argue that as a taxed good, drinking tea was a contribution to the war effort.

Thousands of conscientious objectors refused to perform military service, usually on moral or religious grounds, as conscription laws enlisted 2.5 million extra British troops from 1916 onwards.

By March 1916, the British Government was desperately short of soldiers, conscription was introduced and all able-bodied men, aged between 18 and 41, were ordered to join the war effort.

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To be exempted from the fighting, conscientious objectors had the task of publicly proving to an often hostile tribunal that it was conscience and not cowardice that spurred their refusal to fight.

The only others who could be exempted were the sole carers of dependants.

Papers featured in a new exhibition at St John's College at the University of Cambridge reveal that tribunals asked questions about tea-drinking habits in an attempt to undermine and ridicule people who applied to prove their conscientious objection.

Francis P White was a 23-year-old undergraduate at St John's College in 1916, and he was a conscientious objector on religious grounds.

He kept a diary and collected press clippings, including one from the Cambridge Weekly News, 1916, which reports on his own hearing along with those of three other students from St John's.

All four men had already been granted exemption from combative service, but the military was appealing against the decision on the grounds that they were not "bona fide conscientious objectors".

Bizarrely, the crux of the argument seems to have rested on whether or not they drank tea.

As a taxed good, consuming tea was seen as a contribution to the war effort, which, for the tribunal, equated to 'providing money for someone else to fight'.

When the appellants queried how it was possible to live without paying these taxes, they were told that there was always water - "nature's drink".

During his tribunal, Francis was asked if he had attended meetings for a society of conscientious objectors at St John's College.

He denied any knowledge of such things, leaving his interrogators stumped as to "how it is they all come from St John's?".

However, hidden between the pages of his diary, Francis kept his invitations to secret meetings to "consider procedure before the tribunals", which were held in the rooms of Fellow of the College, Ebenezer Cunningham.

Years later, when he came to write his memoirs at the age of 90, the only thing that Ebenezer - who was also a conscientious objector on religious grounds - could remember about his own tribunal was a baffling question about tea: "The chairman asked me, 'Do you drink tea?' I said I did, to which he replied, 'Well, if I had a conscience, I would not drink tea.' I did not quite understand his objection."

The diaries will be displayed as part of the Cambridge Festival of Ideas.