I would say 1942, take the food bowl out there should be a date and makers mark on the bottom of that as well.
Got one of these the other week for a mate of mine it had a 1943 bowl and a 1918 canteen.
deffo 43 dated even better when its free,and complete,cool field gear,regards dave.
Welcome to my world! Doesn't it feel good saving this stuff from oblivion?!