His premature death follows more than a decade of service to union causes.
After graduating from the University of Leicester, he became a law lecturer at Manchester College of Arts and Technology, a position he held for the rest of his academic career.
He joined the national executive of Natfhe in 1997 at the age of 29. In 2002, he was elected president of the union, which in 2006 merged with the Association of University Teachers to become the University and College Union (UCU).
In 2005, he left the union and the country to teach English as a foreign language in Madrid, where he lived until his death. During his time in Spain he continued to travel back and forth to London, and to work for Justice for Colombia, a coalition of trade unions that supports Colombian social justice campaigners.
The countless messages of condolence pouring into UCU headquarters since news of his death became public show that he was not forgotten after his departure to Spain.
His wit and irreverence won him many friends, while former Natfhe staff had particular cause to remember him for his tireless work on the union's pension scheme, which at one point faced crisis.
As Natfhe's first "out" gay leader, he was a tireless campaigner for gay rights and one of a generation of activists who helped move the union's gay agenda from reformist to liberationist. He led the union's campaign for the repeal of the controversial Section 28 of the Local Government Act 1988, which prohibited "the promotion of homosexuality" in schools.
Mr Kelly was committed to the equality agenda as a whole and was chairman of the Equality Advisory Council for two years. One of his main interests, both personally and professionally, was disability rights.
His good friend, UCU equality officer Kate Heasman, said: "He was a fantastic speaker: very witty and humorous. At the Disability Rights Commission he talked about government policy being all fur coat and no knickers."
While his approach to politics could seem light- hearted, he had a keen eye for detail and was a master of efficiency, with little appetite for drawn-out meetings. "We always used to struggle with the post-conference AGM, which is always a very bureaucratic affair," Ms Heasman recalled. "Gerard got through the whole business in 40 minutes. Everyone's been trying to emulate that ever since."
UCU president Sasha Callaghan said: "Gerard was kind, clever, strong and funny, and we will miss him desperately."