The full title of the key includes the phrase ‘Painted by T. J. Barker Esq. K.L.H. from Photographs and Sketches taken in the Crimea expressly for this picture by Roger Fenton Esq.’ In his letters home, Fenton refers to making sketches whilst in the Crimea but none are known to have survived.

The key was designed to fold out like a map so the viewer could stand in front of the painting or print and compare the two. The name of each individual depicted is given in the key and some of the topography, which includes the besieged city of Sevastopol, is also identified.