A decision to axe a mixed choir at St John’s College, Cambridge, in an attempt to make room for a “broader” range of music has been condemned as “fundamentally regressive” by the former archbishop of Canterbury Rowan Williams, Sir Simon Rattle, Dame Sarah Connolly and Aled Jones.

The decision to cancel funding for St John’s Voices – which has male and female singers and has been running since 2013 – will “diminish” choral music at the college and has left its members “devastated”, according to an open letter.

The letter says the decision in 2022 to allow female singers in the separate St John’s College Choir has been “weaponised” to justify the disbanding of St John’s Voices, whose members have launched a petition to save it.

St John’s Voices has 14 female singers who will be left without an outlet when the choir ends in June 2024.

Addressed to the college council, the letter states: “We are devastated by this decision, which we believe is a fundamentally regressive move for the college, the choral community in Cambridge, and the wider arts provision for women in the UK.”

The college took the decision after a review in 2023 and said the step had been taken “to adopt a broader approach to the provision of co-curricular opportunities in music for our students, including in different genres”.

St John’s College declined to comment when approached by the Guardian, and there has been no confirmation of what that “broader approach” would mean in practice.

That lack of clarity was criticised in the letter, which called the decision-making process unreasonable, while some reports have pitched the row as a battle between tradition and the more progressive ideals of diversity and inclusion.

“A British choral tradition with equal opportunities is something that St John’s Voices should be championing, not looking to diminish,” the letter continues.

“It is upsetting that a remarkable step forward in the choral world (the admission of female singers into SJCC) has been weaponised against the very existence of another ensemble, supposedly in the name of broadening opportunities.”

Other supporters of the letter, which was posted on Wednesday evening and calls for the decision to remove funding to be reversed, include the broadcaster Alexander Armstrong and the host of the BBC reality show The Choir, Gareth Malone.

The director of the choir, Graham Walker, will lose his job when the choir is disbanded at the end of the Easter term. “Terminating SJV will leave over 30 members without a choir, its director redundant, and a hole in the musical life of the college and the wider university,” the letter says.

The choral tradition at St John’s dates back 400 years but it is only since 2013 that women have been allowed to take part. Aquila, an all-female a cappella group was founded in 2017 but is a “secular vocal ensemble” and not part of the choral tradition.

The issue of male-only choirs continues to be divisive, with the tradition clashing with institutions that have signed up to equal opportunities charters.

Anne Atkins, whose father was head of King’s College school, Cambridge, recently wrote about not being allowed to sing in its choir, which is still male-only, continuing a tradition that stretches back to Henry VI who decreed there should be 16 boys in the choir.

Other choirs have become inclusive recently but “there are still comparatively few opportunities for girls in our major choral institutions”, wrote Atkins.