Three hours after graduating from Cambridge University, an email pinged into my inbox. Failure to vacate my college room by 10am the next morning would result in a £100 fine. Having spent the past two summers employed at Oxbridge language schools, I knew why: edu-businesses needed to set up shop in college rooms.

Private summer schools, pitched at the sons and daughters of the global elite, offer an Oxbridge experience at eye-watering prices (nearly £10,000 for a four-week programme). Both Oxford and Cambridge universities told me that individual colleges are responsible for their decisions to accept money from private companies which rent their facilities. These colleges already own a combined £21bn in wealth – more than the combined investments of the other 22 Russell Group universities, and enough to pay the tuition fees of every home and international student in the UK with £3bn to spare.

Instead of pocketing the extra cash, what if these already wealthy colleges used the summer period to offer subsidised facilities to access courses for disadvantaged students instead? The Sutton Trust told me that between 2006 and 2016, students attending UK summer school access schemes were four times more likely to apply to a top university, four times more likely to receive an offer from a top university, and four-and-a-half times more likely to accept the offer. Students who attend the oversubscribed Sutton Trust summer camp are 53% more likely to go to a leading university and 80% more likely to achieve a 2:1 or higher.

As an example, I sent an FOI request to Oxford’s Brasenose College, and learned that it provides just 200 students from UK state schools with accommodation under its UNIQ access programme, compared with 619 private students with edu-businesses. UNIQ says it takes 1,100 pupils on average in the summer in colleges across Oxford and 250 on average in the spring. Meanwhile, the only summer school with which Cambridge is officially associated is the Sutton Trust, which sends 540 students annually. These schemes both prioritise young people who have been in care, who are eligible for free school meals, or who are young carers.

Robert Verkaik, author of Posh Boys: How English Public Schools Ruin Britain, argues that this type of residential access work, available right on Oxbridge’s doorstep, is vital in preparing state school students for a major cultural adjustment. “Reading a degree at one of the grand colleges of Oxbridge, steeped in hundreds of years of tradition and learning, can be culturally very unsettling,” he writes.

Oxford and Cambridge are taking steps to improve their record on widening access through a number of innovative schemes, including the 100 extra places that Cambridge is targeting towards students from disadvantaged backgrounds through clearing and Oxford’s new foundation year for disadvantaged students. But opening up the residential schemes to a wider range of prospective students would be a longer-term approach. Colleges could go even further by committing to spending any money they receive from edu-businesses to widening access schemes.

An Oxbridge education propels graduates into elite professions: the reality is that 71% of senior judges, 57% of the cabinet and 51% of diplomats all come from 1% of students. If these institutions are responsible for creating our political and legal decision-makers then they are responsible for the diversity of these professions. They owe it to society to produce graduates who will be more representative of the population they will serve at the highest level in through their careers.

Instead of renting out their facilities to edu-businesses which promise wealthy international students “specialised application help”, it would be fairer if Oxbridge colleges used the summer break to give more young people from disadvantaged backgrounds the taste of life at one Britain’s top universities.