REPRO White cotton, ration bag. These were used to carry dry rations (tea etc) in the field and could be used to hold the mess tin (as illustrated). Stamped inside with makers name and WD arrow and dated 1940's.

Made from strong white cotton fabric, has cotton tape at the neck of the bag to tie it up.

I also sell these cheaper as a set to include the KFS bag and sewing kit, see my other listings.