A Whitehall sleaze watchdog is to review its guidance on MPs' second jobs in the wake of the appointment of former chancellor George Osborne as editor of the Evening Standard.
But the chairman of the Committee on Standards in Public Life insisted that the review was not prompted solely by the Osborne case, saying that it had been under consideration for some time.
Lord Bew said the committee wanted to look again at its 2009 guidance that second jobs were acceptable so long as voters were informed about them at the time of the election. And he said that it would consider what was the "reasonable limit" that could be applied to the extent of MPs' outside interests.
Inviting submissions from the public to the review, Lord Bew said: "We will make a further submission on 'reasonable limits' for outside interests to the Commons Committee on Standards' on-going inquiry into the Code of Conduct for MPs. We will be holding a short review to inform our submission.
"It is for the Advisory Committee on Business Appointments, the Parliamentary Commissioner for Standards, and the House of Commons Committee on Standards to rule on individual cases."
Asked on BBC Radio 4's Today programme whether his committee was acting in response to Mr Osborne's appointment, Lord Bew said: "We have been paying attention to this for some time and the issue is the important thing for us, rather than any individual case.
"In 2009, we were asked by the Government as a committee to look at this question and the compromise we put forward then was that second jobs could be OK provided this was made clear to the electorate at the moment of the election.
"The question for us, and it's not just a function of the recent case, is has that compromise been working properly? Do we need to look again at what the reasonable limit might be for an MP's outside interests?
"Even in terms of the public who have been writing in to us in recent times on this subject, a lot of the letters don't mention the recent case. They are concerned about the issue and they have different views on the issue.
"The fundamental principle is that the electorate decides who should represent their constituency, but they should have the facts in front of them."
Lord Bew said that the committee had previously taken the view that it was "not entirely desirable" to have a class of professional politicians with no experience of other occupations from careers outside Parliament.
But he said: "It is clear that the public's attitude has shifted on this matter and is more negative about it, although I can tell you from the letters we receive that the public is still divided on this issue."
He pointed out, in an apparent reference to Foreign Secretary Boris Johnson, that "there have been MPs in past who edited things like The Spectator very effectively and nobody at that point regarded it as a major problem".
But he added: "We now need to have a proper review. We want to hear from the public and we want to engage also with the regulatory bodies ... because there's an issue now about the Code of Conduct for MPs and how it deals with this particular issue."