This is a correction to an earlier post I wrote on female despatch riders.
Various experts (including Barbara Legrand a WW1 battflefield guide) have stated on the Facebook page for the Lost Diggers of World War I that this woman is most likely a French mademoiselle dressing up for fun by wearing a corporal's uniform and cap and she isn't a despatch rider herself.
It just goes to show how images and photographs can be misinterpeted, especially if one doesn't examine them closely enough or isn't an expert in the era!
This is not to say there were no female despatch riders at all during First World War, and women riders most certainly played a very important role in the Second.
The Wrens were among the first.