WW1 Soldier's Personal documents Box

Met a very nice fellow who told me this was his Grandfather's who was a Farrier Sargent in the British army during world war one, being a blacksmith in civilian life. It's in original condition and needs a good clean but opens and shuts well.
Makes a find like this even better when the person who lets it go loves a to tell all about it's history. Apparently all the soldier's personal documents and effects went into this box when going into battle?