In 1897, Oscar Wilde sat down in his cell in Reading Gaol – where he was imprisoned for “gross indecency” with another man – and began De Profundis (“Out of the Depths”), his powerful epistolary outpouring to his lover Lord Alfred Douglas (“Bosie”). “It is always twilight in one’s cell,” wrote Wilde, anguished and ashamed, “as it is always midnight in one’s heart.”

The incarceration of Prisoner C.3.3. (the number assigned to Wilde, who wrote his long poem The Ballad of Reading Gaol upon his release) immortalised Reading Prison, as it became known. So when James Lingwood and Michael Morris, co-directors of the ceaselessly enterprising arts organisation Artangel, discovered that this remarkable, cruciform Victorian structure, which had been empty since the prison’s closure in 2013, was due to be sold off by the government, they sensed an opportunity.

After persuading the Ministry of Justice to let them mount an extraordinary temporary group exhibition within the institution, they received the keys to it at the beginning of last month. The finished show, Inside: Artists and Writers in Reading Prison, will open to the public on Sunday.