He grew up in the close-knit community of Blantyre, where his parents insisted that he stick with his education irrespective of his sporting talent. They instilled in him a persistence that helped him pass his 11-plus at St Joseph's Primary, taking him to Our Lady's High in Motherwell.
He followed fellow pupils Bobby Murdoch and Billy McNeill to Celtic, for whom he signed in 1960, but also headed to Glasgow University, studying subjects including English, history and Spanish. He went on to graduate as a teacher from Jordanhill, then took up a placement in the tough Calton area of the city.
At Celtic he was a capable defensive stand-in for McNeill, but the captain's excellence meant he was restricted to 41 games in a seven-year spell. He moved on to West Ham United in London, where he also worked at St Bonaventure's in Forest Gate, a multicultural school that gave him the chance to teach O-level Spanish and A-level English.
He retired from playing football after spells at Dunfermline Athletic and Dumbarton, and became an English and modern languages teacher at St Bride's High in East Kilbride and St Patrick's High in Coatbridge.
He moved on to the post of deputy head at St Ambrose High, also in Coatbridge. Even as a senior manager, however, he was clear that he wanted to continue in the classroom.
His upbringing, and the way people looked out for each other in Blantyre, turned him into a natural at pastoral care, and he served time as a principal guidance teacher.
As a teacher, he did not draw attention to his sporting career, despite the kudos it invariably earned him with boys in particular. If a pupil brought up the subject of Celtic, he would rapidly divert their attention to Shakespeare; pupils always knew that Mr Cushley expected hard work.
He retired from teaching in 2003 and returned to Celtic Park as an education and welfare officer, where he was well suited to helping put the club's young players on the right road.
Last summer, he was diagnosed with motor neurone disease, which had already claimed the life of the legendary Celtic winger Jimmy Johnstone. Mr Cushley was a devout Catholic and took strength from his faith in the face of serious illness. After a dignified battle, he died in the early hours of March 24.
He is survived by Mary, his wife of more than 38 years, his sons Jonathan and Stephen, daughters Marie-Clare and Joanne, and two grand-daughters.