In managing what others say is the potential for a serious conflict of interest in his Building and Construction portfolio, Maurice Williamson has followed Cabinet rules to the letter.
He has bent over backwards to ensure his directorship in Holyoake Industries, a supplier of heating and air conditioning systems, falls within conflict of interest guidelines laid out for ministers in the Cabinet manual.
Labour isn't buying it. The Opposition party says while Williamson might well argue he is operating within the rules, there is no question he is still in breach of the spirit of those rules.
Williamson sees things rather differently. It seems to be almost a point of principle with him that he not be forced to divest himself of the directorship because opponents suggest there is a perception of a conflict of interest when he has made every effort to be transparent in order to demonstrate there isn't one.
As required by the manual, Williamson declared the directorship - which predates his appointment to the Building and Construction portfolio - in the MPs' register of pecuniary interests.
He informed the Prime Minister who gave him permission to keep the directorship. He advised the Cabinet Office which duly conducted a more than cursory investigation into the advisability of him retaining the role before deeming it okay.
Williamson says if a potential conflict of interest arose in his portfolio, he would order officials not to give him the relevant papers and exempt himself from discussions. Decision-making would be delegated to another minister. Such circumstances had yet to arise.
According to the manual, the point at which a minister should divest himself or herself of a shareholding or directorship is when a conflict of interest is "significant and pervasive". That does not seem to be the case - as yet.
Williamson is adamant he has played things by the book - literally. In Labour's view, that is not good enough. A minister being a director of a company which operates in the sector for which the minister has responsibility is just not a good look. It smells. It is unacceptable. Simple as that.