For my head on a silver plate
This refers to John the Baptist. King Herod’s great-niece Salome asked for the head of John the Baptist on a silver platter — paintings depicting such were very popular in the Middle Ages.
More symbolically, revolutionaries want the narrator deposed and dead — given the album’s French revolutionary themes, this might refer especially to Louis XVI, who was beheaded in 1793 by guillotine. Another extremely famous beheading of a monarch in European history is that of Charles I of England (executed 1649).
However the Delacroix painting depicted on the album cover is about the 1830 July Revolution — wherein Charles X was exiled, not murdered.
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