I saw another thread where a smaller inner tray from a zebra billy was used in conjunction with a large billy to make an oven. Exellent idea, but I don't have another billy to use as the inner shelf. I tried the pans from my trangia and found that the inner pan in the two pan set fits very snugly into a 14 cm billy, and the lid is also a very snug fit. This gives the option to cook two things at once in vaster quantities, the little tray that comes with the zebra is a tad on the shallow side.
Mine is on the cooker at the moment with mixed beans in the trangia pan and rice in the bottom, the sausages are under the grill and it's cowboy food for dinner tonight. What's that Mungo, the sausages are burning? Right, I'm off!