Chelsea burned off competition from Manchester City to sign Sunderland junior goalkeeper Toby Bell earlier in the summer.
The Black Cats allowed Bell to leave for London, where Chelsea’s offer included a place at a top West London school.
City were also keen, but Chelsea convinced the Bell family about moving south.
A compensation fee was agreed, which includes a hefty bonus should Bell, 15, eventually play for England.
Sunderland also have 16 year-old Matty Young now rated as senior third-choice keeper.