The photo shows a P37 pattern canvas carrying bag with padding and insulation for serving hot meal food rations in the field.
During combat situations, when hot rations could not be delivered to men in the field by truck, this pack was used to carry a single (or double) ration canister. The pack is constructed of canvas with fibre stiffening pads in the back and bottom to help maintain the shape of the pack.
It is likely these packs were also used for other tasks in combat, such as carrying mortar rounds and other types of ammunition.
Meals at the front were generally good under normal circumstances. Cooked a mile or so to the rear, the rations were brought up piping hot by various ways. The battalion cooks were capable, and although there were many times when conditions limited meals to cheese or bully-beef sandwiches with the inevitable tea or coffee, generally the cooks could bring up a roast beef or mutton dinner with all the trimmings including a dessert. With this carrier the mail and the daily issue of “The Maple Leaf” were brought up to the front as well as the rum ration.
This carrier has room for two metal containers as shown in the museum in the “Food Services” display cabinet..