A kettle designed to be boiled on a hob. A lid on the top is removed to fill the kettle and on the end of the spout is a device which emits a loud whistle when the water is boiling. This ensures the kettle is not left to boil dry.
The kettles were most widely used on gas hobs between the 1930s and 1960s, prior to the widespread use of electric jug kettles which automatically switch off when the water is boiling. They are still sold and in use today for all types of hob and many colours.