After being convicted of the murder of Louise Surgey (his 62-year-old landlady) at Nottingham Assizes, Gnypiuk was hanged by executioner Harry Allen on 27 January 1961.

Afterwards, his body was buried in an unmarked grave within the walls of the prison, as was customary.

A number of prisoners then jumped on the officer, assaulted him and dragged him into a cell and took his keys.

The Trust also labelled Lincoln as the nation's most overcrowded prison, holding 13 inmates over its maximum capacity of 738.

Lincoln is a Category B local prison holding adult male remand and convicted prisoners from the courts in Lincolnshire, Nottinghamshire and the East Riding of Yorkshire.