Answer:
The British, Welsh and Scottish children were required to carry around a box on a strap. The box had their name and other pertinent information on it. Inside was a gas mask that fit each child. The Mask had their name too. The children were taught by the adults how to put it on when they heard the sirens and when they went to the underground bomb shelters. Very young kids had their gas masks carried by adults.
Some kids took their gas masks with them when they were evacuated if they were too frightened to leave them home.