Answer
The author of the letter is an unnamed African leader who is writing to the Queen to appeal for justice and to remove the line that is ruining his land. The individuals and groups mentioned in the letter are Sir Harry Smith, Warden, Boers, Stkonyela, Korannas, Mantans, and Nehemiah. These individuals and groups impact the meaning of the letter by demonstrating the injustice and oppression the African leader is facing. It is unclear if the letter was successful in fulfilling its purpose, as the outcome is unknown.