Sorting out I realised I had quite a collection of mess tins so I thought I'd share them with you. Please feel free to add more variants if you have them!
First up is the classic D-shaped mess tin used from the Napoleonic wars until just before WW2. Interestingly this one is actually dated 1940.
Next is a cavalry mess tin, again with a late ate of 1941. Unfortunately I only have the dish half of this:
Below is the standard tin plated mess tins used by most British Forces in WW2:
Next is an unusual Indian oval aluminium mess tin dated 1945:
Finally we have the standard aluminium mess tins introduced as part of the 44 pattern jungle kit and still used today:
Hope these are of some interest to you.