Nicholas Smith, 66, of Malestroit, France, carried out the assault on a pupil at Chetham's School of Music between 1976 and 1978.
He was arrested by detectives investigating historical sexual abuse at music schools in Manchester.
Smith was sentenced to eight months in prison at Manchester Minshull Street Crown Court.
The court heard that Smith's victim went to police after the death of violinist Frances Andrade in January 2013.
Mrs Andrade had accused former Chetham's choirmaster Michael Brewer of sexual abuse and took a fatal overdose after learning the jury in his trial was instructed to find him not guilty of several charges.
Brewer was jailed for six years for five counts of indecent assault.
Smith's victim, who knew Mrs Andrade at school, told police her death was like the "curtain of a stage lifted".
The court heard the assault by Smith, when his victim was 15 and he was 30, took "minutes" but ruined her life.
Police said the attack took place while the girl was staying with Smith and his wife at a cottage in Derbyshire.
Smith's barrister Neil Usher said the 66-year-old's "reputation lies in ruins".
"He has gone from being a celebrated and much sought-after conductor here and abroad to being unemployable [and] friends who held him in high regard will not look at him again."
Jailing Smith, Judge Peter Lakin said he had "breached the trust placed in you in a most serious way".
He said Smith's victim had been "highly vulnerable".
"When you were alone with her, you cynically took advantage of her vulnerability and subjected her to a deeply unpleasant and frightening ordeal.
"You pushed her to the ground, dragged her clothes up and then fondled and kissed her exposed breasts.
"This was a forceful sexual assault by someone in authority."
Speaking after the hearing, Det Ch Insp Jamie Daniels said he could "understand why people have drawn comparisons between Michael Brewer and Nicholas Smith".
"Smith, like Brewer, took advantage of a homesick young girl in a location away from school grounds while she was isolated and vulnerable."
A conductor who admitted indecently assaulting a teenage girl at a music school in Manchester has been jailed.