Nurses, a Girl Guide and a Boy Scout in a novelty band of domestic utensils.  This is almost certainly part of a carnival to collect funds for their hospital.  The notice 'Take Cover' dates it to the Great War, 1914-18, and a pencilled note on the back '9 Cedar Rd Clapham Common' probably locates it in south London.  Sale of the postcard would have added to the funds.
From Reg Hall Collection.