Tensions that resulted in the sacking of the secretary of the Department of Agriculture can be traced back to a decision by the prime minister’s office to appoint former environment department secretary Dr Paul Grimes to “babysit” the agriculture minister, Barnaby Joyce, government sources have suggested.

Joyce has praised Grimes as a “good man” and a “good public servant” and said the problems between them were because they did not have the “same skill set pertaining to agriculture”. Grimes, in a letter to staff after his sacking, said he “agreed that the minister would be better supported at this time by a new secretary with a different background and set of policy skills”.



The prime minister, Tony Abbott, sacked Grimes, a long-serving and respected public servant, from his job as secretary of the Department of Agriculture on Friday, because there was “no realistic prospect” he could have a “relationship of strong mutual confidence” with his minister, Joyce.



The sacking followed Grimes’s request for a special Senate committee meeting because he had information “highly pertinent” to a long-running saga involving changes in Hansard to an incorrect answer given by Joyce. Labor has alleged that Joyce may have misled the House of Representatives by insisting he had no knowledge of the corrections requested by his staff.



Grimes was appointed after the government sacked the former agriculture department secretary and highly regarded public servant, Andrew Metcalfe, soon after the 2013 election – one of three departmental heads sacked at that time. Metcalfe was reportedly sacked due to his previous role as the head of the immigration department under Labor rather than his time in agriculture.



Several government sources told Guardian Australia they believed Joyce’s style and personality would have been better suited to working with Metcalfe than Grimes, and the decision by the prime minister’s office to appoint Grimes to oversee, or “babysit”, Joyce had been a “big mistake”.



Joyce sought to explain why Grimes had been sacked in an interview on ABC radio on Monday.



“Because there was a difference of how we believe agriculture is to be pursued. He is a good man, he does a good job, but I want to make sure that there’s a right relationship between the minister and the secretary to try and deal with some of the big issues that we have before us in agriculture … I think that Dr Grimes is an incredibly decent and capable person, and agriculture itself has a certain requirement of skill sets. We are not endowed by God with every skill set for every possible department, and that’s something that even Dr Grimes agrees with,” Joyce said.



“It has to be the skill sets of a person who is driven by the issues of agriculture with a minister who is obviously – I am – grew up on the land, driven by the issues of agriculture. It’s quite simple, that there has to be the same skill sets of the minister that the secretary has that is absolutely pertinent to the issues pertaining to agriculture, and what other reason do you want?” he said.



Guardian Australia revealed the full text of a letter sent by Grimes to the committee chairman, senator Bill Heffernan, on 2 March in which Grimes said he had “highly pertinent” information about freedom of information requests by Fitzgibbon for information and documents relating to the process of changing the Hansard. He said the information related to documents not provided as a result of those requests.



But when the committee reconvened last Wednesday as a direct result of Grimes’s request – with a much larger turnout of Coalition senators than normal – Grimes did not provide significant new evidence. Some of the committee’s questions were taken on notice, meaning written answers will be provided by mid-April.



It is understood Labor has written to the Senate privileges committee asking that it look into whether Grimes was in any way intimidated or improperly influenced between his letter requesting the committee hearing and when he gave evidence.



Termination of a departmental secretary requires that both the secretary of the Department of Prime Minister and Cabinet and the public service commissioner report to the prime minister, who then makes a recommendation to the governor general.



Asked about the sacking during question time on Monday, Abbott said: “In the previous parliamentary sitting fortnight the secretary of my department drew to my attention that there were some issues between the secretary of the Department of Agriculture and the minister for agriculture. I asked him to look into these issues, he made a recommendation to me and that recommendation has been acted on … This matter was handled entirely by the secretary of my department, as it should be.”



Paul Barratt, who was sacked as the secretary of the Department of Defence under the Howard government and challenged the decision in the federal court, said the sacking would have a “chilling effect” on the public service.



“What it all boils down to is that a departmental secretary is a tenant at will and you can be out of a job in 24 hours. Of course that has a chilling effect on people’s willingness to give frank and fearless advice,” he said.



“Everyone now knows the minister doesn’t have to say why he has lost faith in you, whether it is accurate, whether it is fair. He or she just has to say that they have.”



The leader of the opposition in the Senate, Penny Wong, said the sacking was “outrageous” and claimed it was part of a pattern of government retaliation against anyone who called them to account.



Several ministers who had worked with Grimes over the years have praised his professionalism and impartiality.

