Cambridge academics and students have called for the reform of the university’s collegiate system after a don accused of sexually harassing undergraduates was readmitted to his college less than two years after being permanently excluded.

Dr Peter Hutchinson agreed to his permanent exclusion from Trinity Hall following allegations that he had breached a ban preventing him from contacting undergraduates.

The college has now said the decision to remove him had “not been agreed with Dr Hutchinson and was incorrect”.

One former student, who had complained about his alleged behaviour, said the decision was an insult and undermined the protection of female students at the college.

The move has provoked more than 150 current and former Trinity Hall students, fellows and staff to sign a letter calling for Hutchinson’s removal. They have also called on the college to “critically review” how it handles complaints of sexual misconduct and how it supports student victims.

Hutchinson was banned from teaching undergraduates and attending social events where they were present at the college in 2015 following a formal complaint by 10 students who detailed separate incidents of “inappropriate, sexual and sexist comments” he had allegedly made.

The college’s senior tutor, Dr Clare Jackson, said in December 2017, after allegations that Hutchinson had breached the sanctions, that he “will not be present in college at any time in the future”.

The college has now said that Hutchinson will be able to enjoy the “rights and privileges” associated with his position as an emeritus fellow. It said: “Dr Hutchinson will continue to attend certain college events and to exercise his dining rights, but will not attend events primarily aimed at students or alumni except by agreement with the college.”

Cleodie Rickard, 23, one of the 10 students who complained about Hutchinson in 2015, said: “I am absolutely outraged and insulted that [the] college would believe this would pass us by and we would not act on the news. I am incredibly disheartened that yet again, after a four-year process to get him removed, the forces of power and patronage win out over empty commitments to zero tolerance and support and safety for students of the college.”

The human rights barrister Dr Charlotte Proudman, a junior research fellow at Queen’s College, called Hutchinson’s reinstatement a “slap in the face for survivors of sexual harassment”. She added: “The college has given fellows a licence to abuse their power with impunity. Women students are not safe in their own colleges. Next time the college could be responsible for irreparable harm. We need urgent reform.”

Dr Priyamvada Gopal, a reader at Cambridge’s English faculty, said there was more chance of a “predatory culture” flourishing in colleges because it could not be addressed by the university centrally.

She said: “Colleges often tend to act in ways that counter the central university’s efforts to address problems, including around sexual harassment. It is time for the university to take a more proactive role in addressing collegiate culture and its abuses. Collegiate autonomy acts to cover a multitude of sins and this won’t wash in the long run.

“Without further reforms and clear safeguards, including external monitoring, the safety conditions of students vulnerable to sexual harassment will not improve.”

Her views were echoed by Dr Tiffany Page, a member of the 1752 Group, which campaigns against sexual harassment by university staff. She said Cambridge students were being failed by colleges.

“Peter Hutchinson should be removed as an emeritus fellow and there should be policy in place to ensure this never happens again,” said Page, a sociology lecturer at the university. “The spotlight needs to be shined on Cambridge colleges, which have so far managed to escape investigation into their treatment of students and accountability for preventing sexual misconduct and other forms of discrimination against their students.”

A University of Cambridge spokeswoman said: “The colleges are all semi-autonomous. The college has made [its] decision. The central university is not involved.”

Trinity Hall has been approached for further comment.

• This article was amended on 21 October 2019. The main image was changed to show Peter Hutchinson. An earlier version erroneously pictured Old Court, Clare College.