I sensed he saw me as a Black and Tan, the name the Irish gave to the English troops who occupied their country.
The upside was that I knew where I stood with my leader; the downside was the lack of any opportunities for advancement in his regime.
Our next personal clash came at an early caucus meeting. As Prime Minister and also Minister of Finance, he dropped it on us that he proposed to give the then Post Office an extra $40 million to set up a "courier service".
In those days the Post Office managed all communications including the telephone services. So, in Rob's view, it made sense for a courier service to come under the auspices of the government-controlled Post Office.
There was a ripple of concern around the room, especially from most of the 11 new MPs, including myself. I had recently met a couple of chaps who were setting up their own courier service in my electorate. With others I questioned, with my knees knocking, this new expenditure, pointing out that these two constituents were risking their own capital and that we, as a party promoting private enterprise, should not be setting up government competition for a couple of "go-getters".
Muldoon pointed out that "I was wet behind the ears" and that I should follow former PM Keith Holyoake's advice and to breathe through my nose, with my mouth shut, for my first term.
My colleagues and I decided this wasn't good advice and our leader was the only one to benefit from such behaviour. We persisted with our opposition to this government intervention and volte face to National Party basic philosophy.
Rob had his scouts out around the back-bench offices, and received the clear message that our stand was the forerunner of a "more market" approach to economic policy. He backed down.
A report in the Manawatu Evening Standard said: "Yesterday, the Prime Minister told a news conference that the caucus view was that courier work could be done adequately by existing private firms."
It also said: "This decision reflects the fact that the caucus has taken notice of the constitutional views of the National Party which state that the party will encourage the growth of private enterprise and will promote individual ownership."
It was a huge backdown from a man who expected total and unquestioning loyalty from his caucus. The Post Master at the time, Ben Couch, an unquestioning Muldoon loyalist, was less gracious. He was reported in the press as stating, "private couriers have been allowed to move into this market and in the process of expanding, they are making inroads into traditional government postal business". He doubted whether it would be successful.
I had learnt the lesson that by sticking one's neck out in politics and following one's gut feelings, you can get things changed.
I hope this new intake of "wet behind the ears" politicians will do the same.
• Michael Cox was a National MP for Manawatu from 1978 to 1987.