The vetting process by which Toby Young was appointed to the board of the new higher education regulator was flawed and rife with political interference, according to the results of an investigation by an official watchdog.

The commissioner for public appointments’ report castigates the Department for Education (DfE) and regulator the Office for Students (OfS) for failing to delve into Young’s controversial writings and social media postings, and uncovers a high degree of direct meddling by ministers in Young’s appointment and No 10 Downing Street in other nominations.

The commissioner concludes that the OfS’s board appointments, including Young, showed a “clear disparity” in the treatment of different candidates, and that parts of the process “had serious shortcomings in terms of the fairness and transparency aspects” under the code governing public appointments.

The report reveals Jo Johnson, who was then the universities minister, contacted Young about applying for the post and that his nomination was later queried by Justine Greening, the education secretary at the time.

The commissioner also detailed the involvement of Downing Street special advisers in blocking nominees for the “student experience” role on the OfS board, who were blacklisted because of previous involvement with student unions and their expressed opposition to the government’s Prevent counter-extremism programme.

“The evidence presented to the commissioner indicates that the decision on whether or not to appoint one candidate in particular was heavily influenced, not by the panel but by special advisers, notably from 10 Downing Street,” the report concluded.

Emails and memos “show that there had been a desire amongst ministers and special advisers not to appoint someone with close links to student unions, such as the National Union of Students”.

Young’s appointment was announced by the DfE at midnight on New Year’s Eve, when the powerful new higher education regulator was formally launched.

Young’s inclusion on the board immediately attracted sustained public controversy, with critics highlighting Young’s Twitter account, containing salacious and crude comments about women, and Young’s writing in support of what he dubbed “progressive eugenics”. Eight days later Young announced he would withdraw.

The commissioner found that while the DfE said it conducted online vetting of the candidates, “by its own admission, it did not delve back extensively into social media so it was not aware of the tweets by Mr Young”. The report adds: “However, the social media activity of the initially preferred candidate for the student experience role was extensively examined.”

The commissioner also revealed that departmental emails referred to “No 10 Googlers” in highlighting social media comments by the student candidates. “Notably, no such exploration or research was made on other possible appointees, including Mr Young,” the report states.

“Mr Young’s reputation as a controversialist, in itself hardly a secret, should have prompted further probing to examine whether what he had said and done might conflict with his public responsibilities and standards expected on the OfS board.

“Second, the rapid disclosure of what were described as offensive tweets in the days after his appointment suggests that it was not that hard to find them, that not much delving was required,” the report added.

The OfS and its chair, Sir Michael Barber, also came in for criticism for their part in the proceedings. Barber sat on the appointments panel, alongside two DfE officials. “Regrettably, and contrary to best practice, the panel for the generic non-executive roles was all male,” the commissioner noted.

The report also details the DfE’s repeated efforts to minimise or delay requests for information about the appointment process from the commissioner’s office.

Peter Riddell, the commissioner for public appointments , said: “My investigation uncovered a number of areas where important principles in the governance code were breached or compromised in the appointments to the board of the Office for Students.

“In my experience, this episode is unrepresentative of the hundreds of public appointments that take place each year, but it is important that lessons are learned – not least so that talented people from a wide range of backgrounds are willing to put themselves forward to serve on the boards of public bodies.”

A spokesperson for the DfE said: “We welcome the commissioner’s report and will carefully consider his recommendations.”