Originally it was a waterproof military coat invented by Burberry’s uniform department at the request of the British War Office for wear in the trenches by the British army officers in WWI. Overcoats soaked with rain and mud were too heavy and uncomfortable, while normal raincoats were inadequate. Tested against hose-pipes, the proofed material was double-thickness across the back; high storm collars buttoned right across the front with special flaps. Various metal hooks and D-rings allowed the hanging of equipment, and so a tradition was born. Hollywood made it the garment of heroes and secret agents.