The Statement of Standards for Ministerial Staff says staff must not retain a directorship of a company without the written agreement of their Minister and the Special Minister of State. But questioned by Labor Senator Penny Wong in an estimates hearing on Tuesday night, Senator Ronaldson repeatedly refused to say whether he had signed such an agreement. Senator Wong also produced evidence that Mr Furnival may not have fulfilled a requirement of the standards that staff divest themselves, or relinquish control, of interests in any private company involved in the area of their Ministers' portfolio responsibilities. Ms Cain has previously said that when Mr Furnival began working for Senator Nash in September, the couple began a process of transferring Mr Furnival's shareholding in the company to her as his co-director. But Senator Wong produced explanatory notes provided to staff which said transferring shareholdings to a spouse was not an acceptable form of divestment or relinquishment.

Senator Ronaldson also refused to say when Mr Furnival's employment had ended, or even to confirm that he was no longer employed, saying it was inappropriate to discuss the circumstances of an individual staff member. Earlier, Senator Ronaldson said it was ''common knowledge'' where Mr Furnival had worked before being appointed to Senator Nash's staff. ''It was not a secret, it wasn't hidden by anyone,'' he said. He said at the time Mr Furnival was employed, the government staffing committee – which approves all ministerial staff appointments – sought undertakings from Mr Furnival and Senator Nash that ''things would be done to ensure that the conflict of interest, real or perceived, no longer existed.'' But asked whether these undertakings had been recorded, Senator Ronaldson said he did not know and would take the question on notice. He said the staffing committee was also aware of Mr Furnival's shareholding in the lobbying firm, but did not seek an undertaking that Mr Furnival would divest himself of the shareholding, because the couple had already started a process of divestment.

''The couple know what the requirements were,'' Senator Ronaldson said. Senator Ronaldson said it was "not surprising'' that Mr Furnival had not divested himself of the shares, five months after starting work with the Minister, because it was not straightforward to divest oneself of shares in a private company. Loading Labor and Greens Senators are expected to pursue the matter when Senator Nash appears before an estimates hearing on Wednesday. Follow us on Twitter