This illustration is from English illustrator Randolph Caldecott for whom the Caldecott Medal for Illustrators is named. His birthday is today. The Caldecott Society in England has this information about the nursery rhyme on its website:

When Randolph Caldecott produced this book, the Nursery Rhyme on which it was based seemed to be just a children’s song. But, only 60 years previously, when the rhyme about “four and twenty black birds” first appeared, it was full of political significance, based on the “Cato Street Conspiracy” (1820) in which 24 men (one of whom was black) plotted to murder the entire Cabinet at dinner one night. When they were discovered, many of them began to tell about the others in the hope of saving their own lives – hence “the birds began to sing”.
I wish I could make up a seemingly innocent poem full of political significance.