Simon Marshall, the headmaster at the £25,000-a-year school, spoke of the “profound shock and sorrow” felt by pupils and teachers after they learnt of the “heartbreaking news” of his death.
The school’s flag was flying at half-mast on Wednesday as pupils and parents brought bouquets of flowers to lay at its front gates.
Marshall said the boy, who joined Bancroft’s at the age of 7, had demonstrated “commendable dedication to his academic pursuits” and had become a “core member of our community”.
He said his death “will have a lasting impact on us,” and added: “Losing such a young pupil is something we will always struggle to come to terms with.”