Why the animals sing the best of England song slowly and mournfully as they were gathered on the knoll in animal farm?

In George Orwell's "Animal Farm," the animals sing "The Best of England" slowly and mournfully on the knoll as a reflection of their disillusionment and loss of hope. Once filled with dreams of freedom and equality, their reality has devolved into oppression under the pigs' rule. This somber rendition symbolizes their longing for the ideals of the revolution, now overshadowed by betrayal and hardship. Their mournful singing serves as a poignant reminder of the stark contrast between their aspirations and their current plight.