The metaphor compares tea with the entirety of the British empire. It starts by saying that 'tea' should be banished and should go back to Britain "where gold enslaves", meaning where money rules all. The song becomes more broad and loses the specific relation to tea, while attacking Britain's strategy of rule, comparing Americans to being enslaved on a "yoke" (treated like cattle). The final stanza loses the metaphor and is an explicit call to action for everyone to stand up and fight for their freedom.
