mess tin 
noun British
A rectangular metal dish with a folding handle, forming part of a soldier’s mess kit.If possible, also carry: Stove and fuel, signal flares, metal mug or mess tin, torch and batteries, spare matches, survival bag, brew kit, spare food, more ammunition, and extra matches...
- Our work finished about 2 am and we returned to the trenches a hot supper was served to us I picked up the first utensil I could set my hands on which happened to be the common mess tin.
- There were other examples of devices with explosives inside them - a tin of Smedley's plums, lumps of coal, cans of motor oil, shaving brushes and a mess tin.