A tiffin carrier is a traditional multi part lunchbox that was popular around the world at one point, but today is mostly associated with India and South East Asia. It comprises of three separate dishes that stack on top of each other with a lid and carry handle. Recently a batch of British Army tiffin carriers came up on the surplus market, all unissued and covered in thick storage grease. I picked up one of these and after some careful scrubbing managed to get most of the storage grease off, leaving this three pan carrier:

The handle acts as the clamp holding all the parts together, by moving the bar on the handle assembly to one side, the three pans and their lid can be separated to allow the contents to be consumed:

 In Indian culture, the bottom tin is often used for rice, the middle for a curried dish and the top compartment for a sweet. I have found very little reference to these tiffin carriers being used by the British Army, but it seems they were and speculating, it is possible that they were used for light meals in the field whilst on exercise, much like bag meals are today. The food could be prepared back in kitchens, transferred to the tins and brought into the field by lorry for lunch- once eaten the dishes could be collected up and returned for reuse. These tiffin carriers would not be suitable for any sort of active purpose as they would need to be carried, but for one day exercises away from base they would be ideal. The base of each dish has a stores code, date of 1947 and a /|\ mark:

This is repeated on the lid:

The seller of these tiffin carriers includes a photograph of the box they came from, indicating not only the NSN number and official title, but also that they were repackaged as late as 1966: