sentences:  The prototype flag had been made up in silk and was kept throughout World War II by the Civil Aviation Department in a series of locations in London.In October 1948 it was handed to the Ministry of Civil Aviation Library for retention and display.The visible stains on the light blue silk were said to have been caused by water from the fire brigade's hoses used in quelling a fire in the roof at Parliament Square House, caused by a German incendiary bomb, whilst the CAD was accommodated there.