There has been a song school associated with Saint Paul's Cathedral since its foundation in 604.
The Choir School for boy choristers dates from about 1123, when 8 boys in need of alms were provided with a home and education in return for singing the Cathedral Office. Gradually two schools emerged, the Choir School and the Grammar School. For many years they co-existed happily, the choristers graduating to the Grammar school to finish their education, until the latter was re-founded by Dean Colet in 1511 and became Saint Paul's School. (It is now in Barnes and has only a tenuous connection with the Cathedral.)
In the late sixteenth and early seventeenth centuries the school was more famous for its acting than its singing. The Children of St Paul's had their own resident playwrights, performed regularly at Greenwich Palace before Queen Elizabeth 1 and incurred the wrath of Shakespeare and his professional company just over the river. (In Hamlet he rails against the company of 'little eyases' who are roundly applauded for their histrionic efforts). After the Restoration the choristers enjoyed a somewhat chequered history, but a vigorous campaign by the redoubtable Maria Hackett lasting some sixty years led to the re-establishment of a purpose-built school in Carter Lane to the south-west of the Cathedral in 1874. There it remained until the 1960s, when, under threat of demolition due to a road-widening scheme, it moved to its present site in New Change.