By Nick Assinder
Political correspondent, BBC News website
The Derek Conway affair has opened up a major debate on whether MPs, known as "honourable members", should continue to self-regulate their allowances.
Mr Conway will stand down as an MP at the next election
And most in Westminster now seem resigned to the fact that something will have to change. The prime minister, for example, has said he believes there should be "greater transparency" of MPs allowances.
At the centre of the row is the notion that MPs should continue to be allowed to regulate themselves - something recently in the headlines over the issue of their pay.
And, just as is going to be the case with Gordon Brown's planned reforms to the way their salaries are decided, it would ultimately be up to them to vote on whether or not to deny themselves the power to self-regulate.
Many believe they know exactly which way such Commons votes would go - although there is a strong argument being put by modernisers that such reforms are exactly what is needed to help rebuild MPs' reputation and standing in the community.
The new standards watchdog, Sir Christopher Kelly, has already launched the debate by suggesting there may be a case for banning MPs from employing family members.
He has also announced his committee on standards in public life would now investigate the whole issue with a view to recommending reforms.
Such a ban on family members would prove hugely controversial, with MPs fearing it would put another strain on their domestic lives which are already notoriously pressured by parliamentary life.
And it will infuriate those traditionalists in parliament who take the "honourable" bit of their title deeply seriously, particularly those dozens who employ their spouses or other family members entirely legitimately.
MPs vote on their own regulation
Another suggestion, which has won the backing of the Liberal Democrats, is that MPs should simply be required to publicly record the employment of family members.
An alternative suggestion, which seems to have tentative support from Tory shadow leader of the House, Theresa May, is that there should be spot checks of MPs allowances by an external body, most likely the National Audit Office.
Then there is the far more radical, and highly-controversial suggestion, that parliament should directly employ staff which are then allocated to MPs.
There might then be a much smaller allowance available for individuals to employ perhaps a single adviser or aide.
None of the current suggestions has won universal support and there remains a powerful lobby flatly opposed to any further scrutiny of their expenses and allowances.
However, the notion that MPs should be allowed to conduct their financial affairs in near secret, because of that "honourable" tag, has already been challenged.
After much wrangling, the Register of Members' Interests was introduced in 1975 requiring MPs to list "information of any pecuniary interest or other material benefit which (he or she) receives which might reasonably be thought by others to influence his or her actions, speeches or votes in Parliament, or actions taken in his or her capacity as a Member of Parliament".
It was initially so controversial that some senior MPs flatly refused to have anything to do with it or would enter something along the lines of "various external interests".
They all fill it in assiduously now for fear of the consequences of being found in breach of the rules.
It now seems highly likely that a reform of MPs allowances and expenses is firmly on the cards.
Whether the notion of the honourable member will remain is another matter.