Every British tank manufactured since the 1945 Centurion, and most armoured fighting vehicles (AFV), have a boiling vessel (BV) also called kettle or bivvie. It could provide boiling water for beverages, washing or other purposes and, at the same time, heat up tinned or decanted food for the crew. It’s a square,watertight container which holds a gallon of water. It has heating elements and a tap.

The boiling vessel or BV is required on all armoured vehicles of the British Armed Forces.

British really do take their tea time seriously!

Reference:

http://en.wikipedia.org/wiki/Challenger_2

http://www.greenflash.org.uk/bits/stories4.html