Boris Johnson’s ethics chief has revealed his office has been inundated with public messages about ministerial standards in the wake of the Priti Patel bullying scandal and other controversies.

Ex-MI5 boss Lord Evans, who chairs the prime minister’s committee on standards in public life, said there has been “disquiet amongst quite a number of people” in recent months as Johnson resisted calls to sack various ministers.

In one of the most high profile cases, Johnson decided to keep Patel as home secretary despite an internal investigation finding her guilty of breaching the ministerial code after she was accused of bullying Home Office officials by “shouting and swearing” at them.

The PM’s decision sparked the resignation of his independent adviser on ministerial interests, Sir Alex Allan, which was described as “deeply concerning” by Lord Evans.

Labour MP Rachel Hopkins asked Lord Evans whether the Patel case and Johnson’s refusal to sack education secretary Gavin Williamson over the exams fiasco had done “lasting damage to public confidence in the ministerial standards”.

At the Commons public administration committee, Lord Evans replied: “I think there has been concern over this last period because of the number of high profile cases.

“Why do I say that? Partly because of media coverage and that’s always the case.

“But also we have had a very large number of emails and messages to our own website and so there is a concern out there.

“But I don’t feel as a result of that the situation is irreversible or we are doomed to decline on these issues.”

The peer went on: “Judging from our mailbox there is disquiet amongst quite a number of people.

“Is there more disquiet than there was 10 years ago? I think that’s quite difficult.

“The current area (of discussion) in the last few months about the ministerial code and ministerial accountability – that’s the issue of the day in a sense on the standards agenda at the moment.

“Has it undermined public trust? Your judgment on that is probably at least as good as mine.”

Lord Evans also said he shared the concerns of commissioner for public appointments Peter Riddell about the growing number of people being hired to official posts without proper competition.

Riddell last month said he was worried about the appointment of “political allies of ministers” to Whitehall non-executive boards and warned against “unregulated appointments” like the hiring of Tory peer Baroness Dido Harding to run the so-called NHS Test and Trace  service.

“In so far as the commissioner has concerns we would share them,” Evans told the committee.

“As a general principle we think that public appointments should be done on the basis of merit and on a free and fair and open basis.

“But recently there are times when there are immediate and great operational pressures and we recognise that and we wouldn’t want to challenge that at all.

“But even then there are urgent procedures through the commissioner for public appointments to make sure that loopholes are not being exploited.

“I feel uncomfortable at the concerns expressed by the commissioner.

“I do think we need to be very careful not to lose the fair and open procedures for public appointments and whilst it’s absolutely right and proper that ministers should make those appointments and there’s no reason at all why somebody who’s politically aligned should not be appointed, they should be appointed on the basis of being the best candidate and not because they happen to be a friend of the minister or something.”