I'm not trying to play with words, naomi; according to my dictionaries - Oxford and Chambers - reproach does indeed mean criticise, varying from mild complaint to severe upbraiding. (Googling "define:reproach" gives the same answer.) So I'm not asking what it means, I'm saying that it's too vague to have any practical meaning. If failing to act above reproach was a crime, it could never be proved.
Nor do I know how you'd decide what is necessary to perform parliamentary duties. A table and chairs? Hanging baskets? Quite possibly, given that modest entertainment seems to be legitimate parliamentary business, unless you insist your MP live in squalor as a form of punishment.
ludwig, I quite agree that many MPs' actions are indeed below reproach; duck houses, moats, non-existent mortgages and so on. But last time I looked, few MPs were at it on anything like this scale.
Quinlad, I think you're right about the need for transparency; events show the public have a right to know what they're spending their money on. But it's still not exactly an answer, because it depends on how the public feel about it at any given time, which may depend how much other news is around. One week they might think it's ok for an MP to have a KitKat from a minibar; the next the Telegraph might whip them up into righteous fury about it. That doesn't make the system much more transparent.