Boris Johnson’s adviser on ethical standards has questioned whether the prime minister should maintain sole responsibility for the ministerial code days after an outcry over the decision not to sack Priti Patel for bullying staff. Jonathan Evans, the chair of the committee on standards in public life, said the PM having sole discretion over both launching investigations and deciding to punish an errant minister risked looking like “marking your own homework”. His remarks come after Johnson was accused of double standards after telling ministers there was “no place for bullying” in the wake of a damning report into the behaviour of the home secretary. Johnson refused to sack Patel on Friday despite an inquiry by his adviser Sir Alex Allan that concluded she had broken the ministerial code. The prime minister has sole power both to trigger investigations into wrongdoing by ministers, and to decide on what action, if any, to take. Johnson’s decision not to sack Patel set a new precedent because previous ministers who have been found to have broken the code have been sacked or resigned from office. Lord Evans, a former head of MI5, told parliament’s standards committee he was to take evidence on whether to hand both the powers to an independent body similar to those that have been introduced in parliament. “The triggering of an investigation rests solely with the prime minister. The decision on what action to take about that also rests entirely with the prime minister. “In the same way that adjudicating those same issues in the Commons or the Lords looks as though you are marking your own homework, the same concerns could be expressed about the way the ministerial code works,” he said. “There is a problem here … the ministerial code does not have the same independent process which supports the Commons’ code [of conduct] and I think that is an issue which has been overtaken. “Increasingly – we have seen it in the Commons, we have seen it in the Lords and we have seen it elsewhere – an independent element has been introduced. So there is a kind of mismatch between the expectations of what you would deliver from the Commons and what you get from the ministerial code. “So I think there’s a question to be asked about whether there should be more independence, whether the investigative element should be triggered independently, potentially and then there’s the separate but parallel issue of what the response to the actual investigation should be.” Lord Evans said the public would be confused by the fact that allegations of bullying by MPs are investigated by an independent panel, but allegations of bullying by ministers are not. “If bullying is treated in one particular way for MPs in their parliamentary role then why would you want to handle it differently in their ministerial role?” He also suggested there should be more options for punishing ministers who break the code, rather than simply whether or not to sack them. “At the moment it’s rather a binary thing, either you get virtually nothing, really, or you have to resign,” he said. On Friday, Johnson refused to sack Patel after Allan’s inquiry concluded she had broken the ministerial code following bullying allegations across three government departments. Allan, the prime minister’s adviser on ministerial standards, resigned from his post after Johnson contradicted his report by vigorously defending the home secretary and keeping her in her role. One of the justifications Johnson used for defending Patel was the element of Allan’s report that said she had been unaware of the impact of her behaviour because no Home Office official had complained about her. Sources have said, however, that Allan sought to interview the former top Home Office civil servant Sir Philip Rutnam, who resigned after clashing with Patel, but government officials blocked him. Offering what she described as an “unreserved, fulsome apology”, Patel has seized on Allan’s finding that she had received no feedback on the impact of her behaviour. Rutnam, who is suing Patel for wrongful dismissal under whistleblowing laws, issued a statement on Friday that said she was advised not to shout and swear at staff the month after her appointment in 2019, and that he had told her to treat staff with respect “on further occasions”.