Europe of the 1930s was in turmoil, and London, along with the rest of Britain, was preparing for war.
In World War One, there had been two major raids on London in the summer of 1917 made by Zeppelin bombers (a Zeppelin was an airship, a kind of balloon). By 1939, air technology had developed rapidly. The notion of new and improved planes and bombs, capable of even greater destruction directed at London filled people with foreboding. It was clear that the authorities were going to have to prepare themselves for attacks on civilians.
Air raid precautions to protect the people of London were made compulsory by the government as early as 1937. In April of that year an Air Raid Warden service was set up. Just over a year later 200,000 people had been recruited into the service.
The fear of poison gas attacks was another threat to Londoners. Poison gas had been used in the First World War on the Western Front. Consequently, gas masks were provided for all and it was made compulsory to carry them at all times.
Londoners began to build a picture in their minds of what a war would mean for them, how it would effect them in their very homes.
At 11:15am on Sunday 3rd September 1939, on BBC radio, the Prime Minister, Neville Chamberlain, announced the declaration of war on Nazi Germany. At 11:27am, the air raid warning sirens wailed throughout London. Londoners had experienced practice bomb alerts before but this one must have felt different, more real perhaps, as the people filed into the shelters guided by police and ARP Wardens.