King Solomon High deputy head Liam Joughin is retiring after 36 years in Jewish education.
Mr Joughin, who is not Jewish, has spent 15 years at the Redbridge school, having previously served Hasmonean High. School trips to Israel are among his fondest memories.
King Solomon head Spencer Lewis recalled being a student of Mr Joughin at Hasmonean. He praised him for his "enormous" help during Mr Lewis' headship.
"He is an exceptionally modest person who has improved the lives of thousands of young people in an unassuming way. He has been an outstanding teacher, role model and friend."
From the January term, his replacement will be Rabbi Jeremy Bruce, who has been an assistant head at the school since 2007. Rabbi Bruce will continue to have responsibility for student progress at a time when the school's exam results have been improving year-on-year.