Chas is shown playing with the "Sword of Night." This is used by the DC comic hero known as Nightmaster who made his comic debut in Showcase #82 (May 1969). The sword is able to make people tell the truth, deflect magical energies, and warn the user of danger.
Though the stairs of Vulcan shown in the skyline of Birmingham look like plaster, the tall statue of Vulcan is bronze.
The title may refer to Caliban, son of the witch Sycorax, in Shakespeare's The Tempest.
The Birmingham Vulcan is over 118 years old and is the largest cast iron statue in the world. Over the years it has been painted many times (to prevent rust). The paint colors have varied from anglo-saxon pink to aluminum to rust to Vulcan Grey.