The Grand Duke's Special Air Service was spawned by the Duchy of Coventry's need to tie together its far-flung commercial enterprises. Lift is provided to the Coventry Skyship via "firegas," a substance manufactured in a secret process by Sekundar Skyways PLC under contract to His Grace's government; motive power is provided by specially trained dragonelles, creatures that live in substantial numbers in the mountains of Coventry. (They are rather smaller and less intelligent than true dragons -- and do not breathe flame, an important consideration, since firegas is quite flammable.) Their main purpose is the delivery of diplomatic and commercial messages across the world, but they do often carry passengers as well -- for high fees. Exiles living in Coventry often use the Skyship to travel to the site of an uprising or rebellion.