former pupil of a school or college, esp. a public school
The new headmaster of Emanuel in 1954 had himself taught at Harrow, where the strains of `;Forty Years On'; stirred his memory and his loyalties, and was an old boy of Emanuel: nothing would be deliberately done to loosen the ties with the past. BNCI
There, a well-established elementary school was rapidly turned into a small secondary modern school under the same head (an old boy of Banbury County School, of course) and with three forms of entry for pupils at the age of eleven. BNCI
Monty was an Old Boy of the local grammar school. BNCI