English: Bakers checking their yeast, Western Front, during World War I. Three bakers in white uniforms standing at the yeast store. The yeast is in sacks which appear to be laid on a wooden framework around an air vent and a chimney. This may have been some form of device to gently warm the yeast to keep it active. The photographer is unknown, but it may have been John Warwick Brooke, as there are very similar photographs thought to have been taken by him.

This is one of a series of photographs showing the whole process of baking the thousands of loaves of bread needed by the army. In theory each man had a pound loaf each day. In practice the full allowance rarely arrived and the bread was often very stale by the time it reached the Front.
[Original reads: 'Where the yeast is stored.']

http://digital.nls.uk/74549432