Children play on an old German gun and exhibits inside the Imperial War Museum, reminders of the relatively recent World War I.

Sunday 3 September, 1939. The day begins peacefully with people going to church or to the country, but at 11.15am Neville Chamberlain broadcasts from 10 Downing Street the news that Britain has declared war on Germany. The populations listens to him via their radios.

In London, people enter shelters when the area alarm is sounded at the approach of an unknown aircraft. A protective barrage balloon is sent up. Near the Albert Memorial, the ground is dug up and sandbags are filled. Trenches and air-raid shelters are built.

Young men go into military training. Pilots rev up their planes and take off. Covers for gas masks are sold on street corners. Shop windows are barricaded and white lines are painted on roads and cars. Scotland Yard is fortified with sandbags. The aged and infirm of London's hospitals are evacuated to the countryside, along with children, whose mothers find life very quiet without them.

Girls take over driving ambulances and taxis become part of the fire service. A newly-enlisted army member buys his sweetheart flowers before leaving for the front. Sailors leave port.

The National Gallery closes and the paintings are sent to the countryside, likewise the objects in the British Museum.

Ships are camouflaged. In the West End, maps of Europe are displayed in shop windows. Foreigners register themselves as aliens. Pets are collected for evacuation to the countryside. Women don uniforms and take jobs in the services. More troops leave for the front.

As night falls, spotters keep watch, and the night patrol plane takes off. Playhouses are closed, and hospitals stand by, while munitions factories keep working through the night.