Ever since the British Centurion MBT (main battle tank) was introduced in late 1945, all British tanks and most AFVs (armored fighting vehicles) have been equipped with tea making facilities.
The official name of this facility was Vessel Boiling Electric, but it is usually abbreviated to Boiling Vessel (BV). It was unofficially known as a kettle or bivvie. The device draws power from the vehicle’s electricity supply and permits the crew not only to make tea, but also boil water or cook food.
This is particularly important since it allows the vehicle’s crew to produce hot water for washing or drinking purposes and simultaneously heat up tinned or decanted food. All of this can be done inside the vehicle itself, meaning the crew can remain protected from enemy fire. This applies even if there was danger of radioactive fallout or chemical weapons, which were considered a very real threat during the Cold War.
The BV looks like a square, watertight container which holds one gallon (around 3.8 liters) of water.
It is now an official requirement for British AFVs to have a BV installed. This requirement is unique to the armed forces of the United Kingdom.