The Atlantic has published a great collection of photos that might be useful for interwar and WWII gamers:
England's biggest demonstration of its readiness to go through a gas attack was
staged, March 16, 1938, when 2,000 volunteers in Birmingham donned gas masks and
went through an elaborate drill. These three firemen were fully equipped, from
rubber boots to masks, for the mock gas "invasion". (AP Photo)
Undaunted by a night of German air raids in which his store front was blasted, a
shopkeeper opens up the morning after for "business as usual" in London.