In the lead-up to World War II there ... poisonous gas, so by 1938 the government had issued respirators to every man, woman and child in the nation. More than 40 million gas masks were issued.

Now put your books down…and get your gas masks out. Quietly. Now take them carefully out of their boxes - no, no, Isobel, don't drag at it…you show her how to do it, Margaret, will you.