'The only war worth fighting is the class war'.

Pictures of "delicate" graffiti drawn in pencil by conscientious objectors held in Richmond Castle during the First World War have been revealed in a series of pictures by English Heritage, which will preserve the art.

In May 1916, 16 men - mainly from the north of England- were incarcerated in cells at the 19th-century North Yorkshire castle before they were transported to France to face court martial and a possible firing squad.

The graffiti, scratched on to cell walls, features pencil drawings and inscriptions, including slogans, poetry, portraits of loved ones and even a few examples of "dark humour", according to English Heritage.

The prisoners, known as the Richmond Sixteen, included a Sunderland footballer, a clerk at the Rowntree's chocolate factory in York,men held at Richmond Castle before being shipped to France to face court-martial and the threat of firing squad.

His daughter-in-law, Marjorie Gaudie, said: "It is important to remember men like Norman. They were courageous men.

"He acted from the deepest conviction that all life is sacred. He knew it was wrong to take a life and so he refused to fight.

"He was prepared to die for his belief and that took immense courage," she added.

Marjorie Gaudie, daughter-in-law of Norman Gaudie, centre forward for Sunderland FC and one of the Richmond Sixteen, said: “On the eve of Conscientious Objectors’ day it is important to remember men like my father-in-law, Norman Gaudie.

"They were courageous men. He acted from the deepest conviction that all life is sacred. He knew it was wrong