The former teacher’s retirement brings an end to 46 years in education where he had worked predominantly in East Sussex but also in West Sussex, Kent and Surrey.
Mr Diack also taught at Ratton School for 30 years where he led the sociology department for most of that time.
In addition to teaching sociology, Mr Diack taught geography, RE and PSHE while also leading a course in economic awareness for the senior students.
For many years Mr Diack, who graduated from Aberdeen Teacher Training College in 1975, spent his lunchtime playing football with the senior students and was also a member of the staff football team.
Recently Mr Diack was also a panellist on the inaugural wisdom council for East Sussex College
During his time with East Sussex College working in learning support, Mr Diack encouraged students to reach their potential with the Education and Health Care Plan while also helping pupils enjoy their learning experience.
Mr Diack said he is looking forward to developing some hobbies and interests during his retirement including gardening, travel and photography.
The former teacher, who graduated from the University of Aberdeen with a MA (Hons) in Sociology, said he would like to thank all his fellow colleagues for the support they have given him over the years and also wanted to give his best wishes to all his former students.