About twenty years ago, when I was Leader of Somerset County Council, I remember a councillor colleague of mine telling a story about a conversation he had in his local pub. He asked people in the bar how much they thought he was paid as a councillor. Their answers varied, but the consensus drifted to “about £30,000”. The real answer was barely a tenth of that figure.

The great British public is all too ready to believe the worst about their elected politicians, at any level. That’s why episodes like the Derek Conway affair are so damaging. Egged on by an irresponsible and idle press, people are only too happy to believe that “they’re all the same – snouts in the trough”. And if we are foolish enough to have systems so lax or so opaque that it encourages that view, then more fool us.

I am by nature a puritan on these matters. I try to put myself in the position of someone who sees their tax money being spent on “expenses” they find it hard to justify, and react accordingly. But you don’t need to put on a hair-shirt to realise that the present rules invite criticism. Nor should anyone believe that crossing the boundaries is the exclusive preserve of any one party, or that when people are caught fiddling the books it doesn’t rebound on politics as a whole.

I made three suggestions when this story broke last week. Firstly, that we should accept, immediately and without question, the proposal made by the Senior Salaries Review Body that MPs expenses should be subject to spot checks by an independent auditor. Secondly, that we should put an end to the extraordinary rule by which petty cash claims of up to £250 are paid without providing receipts, which would be unknown to any commercial company. And thirdly that, given they are paid from public funds, there is no reason why MPs should not reveal who they employ, provided there are no over-riding personal safety issues. I led the way by putting the names of my staff on my web-site that day.

We could go further. For instance, although there are arguments for employing spouses, provided they do the job they are contracted to do, it is hard to see how the employment of children or other family members can fall within proper employment practice. And should MPs be able to purchase property with the money given to them to live mid-week in London? Too many see that as a neat way of providing an additional pension.

But act we must. The Speaker has now, however reluctantly, opened the door to further reform, but at the same time delayed any outcome until autumn at the earliest. That is too long for some of the more elementary steps, but revolutionary for what I call the “good ol’ boys” who run this place. But we shouldn’t kid ourselves that the public will be remotely reassured until and unless some of these loopholes are addressed, or that they will not still prefer to think the worst of us. As Liberal Democrats, we can at least urge colleagues of all parties not to provide the ammunition though.

David Heath is the Liberal Democrat Shadow Secretary of State for Justice