Final answer:
The riots in the poem are contrasted with the romanticized image of King Arthur's England, a time often depicted in literature as one of chivalry and noble order.
Step-by-step explanation:
The riots mentioned in the poem are contrasted with the image of King Arthur's England. This period is often idealized in English literature and history as a time of chivalry, honor, and a noble social order, which stands in stark contrast to the chaos and violence of a riot. The Romantic era writers frequently referenced such eras and legends to critique and contrast the contemporary societal issues they were confronting. The imagery of King Arthur's England invokes a romanticized past that contrasts sharply with the harsh realities of the present, as described in the poem.