Ministers have been urged to publish the scores of candidates who applied for a top role on Whitehall’s anti-sleaze watchdog, after its chair lamented that the latest appointment – a University of Oxford friend of Boris Johnson’s – had turned it into an all-white body.

Jonathan Evans, who chairs the Committee on Standards in Public Life, wrote to Michael Gove, the Cabinet Office minister, saying some members had “expressed concerns about our lack of visible diversity now as a group”.

His letter, published on Monday, came after City lawyer and former Bullingdon Club member Ewen Fergusson was confirmed as the newest member of the eight-person committee.

The appointment sparked controversy, with a former chair of the committee, Sir Alistair Graham, saying it was a “pathetic” attempt to recruit an old friend of the prime minister’s to an independent body.

Its primary role is advising the government on ethical standards across public life. The group can conduct inquiries, collect evidence to assess institutions, policies and practices, and make recommendations to Johnson where appropriate.

Lord Evans cautioned that “the committee needs to be representative of the people we serve” and pointed out there would be a vacancy on it from the start of 2022, when the term of Jane Martin comes to an end.

“We hope this diversity point can be given due weight by the Cabinet Office in the recruitment of future committee members,” Evans added.

Monisha Shah was the only non-white member of the committee – but she stepped down earlier this year.

Angela Rayner, deputy leader of the Labour party, said that “being Boris Johnson’s mate from the Bullingdon Club should disqualify somebody from serving on the Committee that is supposed to uphold standards in politics and public life”.

She told HuffPost UK: “Out of 173 applicants, there must have been many candidates who were more representative of British society and eminently more qualified than the prime minister’s chum.

“The government should now publish the interview scores received by each candidate – while protecting their identities, and confirm how many of the 173 applicants were deemed ‘appointable’ so we can see whether there was any bias or favouritism in this appointment.”

The Cabinet Office said: “We have received the letter and will respond in due course.”

It has previously responded to criticism of Fergusson’s appointment that he “applied through open and fair competition, following the governance code for public appointments”.

They added: “His application was carefully considered on its merits by the advisory assessment panel, which interviewed him and found that he was appointable.”