A past pupil of Methodist College Belfast has left the school a "transformational donation" of £13.5m in his will.
Richard Henry (Prescott) Kerr was the youngest child of five from a "farming family" and boarded at Methody in the 1940s.
He founded a business which specialised in the nutrients in agricultural feed.
It is understood to be the largest donation in Methody's 156-year history.
Scott Naismith explained in a video posted on the school's website that the school's governors agreed that "in keeping with his interests", that a proportion of the funds would be used for "the promotion of pupil mental health and wellbeing, improving the learning environment through contributions to capital development projects and enhancing the opportunities for pupils of modest means".
"Prescott (as he was known to family) cared deeply about those he loved and gave generously of his time and himself to support and care for them," he added.
"He also wanted to leave behind a legacy that would help to ensure that pupils who attended Methody would be supported in and out of the classroom to thrive and succeed."
After school he attended both Queen's University Belfast and Cornell University in Ithaca, New York.
Mr Naismith said that Mr Kerr worked for Cockburns of Banbridge, producing vitamin feeds for agricultural foods and later set up his own business, Newtech, in 1985.
He passed away on January 24, 2019, peacefully, at Hynetown House, Dartmouth, England and was the dearly-beloved husband of the late Bea, loved brother of Armstrong, Margaret, the late Elro and the late Edmond.
Methodist College said he "excelled academically as well as enjoying rowing in the College 8 and playing rugby" during his time at the south Belfast school.
"Throughout our history, Methody has benefitted from the generosity of past pupils who have made significant, philanthropic contributions to support the development of the school and enhance the opportunities of our pupils,"
"School development is neverending, and the entire College community is profoundly grateful to Richard Henry (Prescott) Kerr."