He laughs at a suggestion that Ministry of Foreign Affairs and Trade (MFAT) might actually start to appreciate him once staff have to deal with the famously sensitive Brownlee.
"I rather hope there are people in the ministry who appreciate me anyway," he says in an exit interview with the Herald.
He says there should be a healthy tension between officials and ministers.
"Officials are there to try and advance the agenda of the country and the Government of the day and that sometimes brings them into conflict with ministers who have got a view about where policy should go or how much time should be wasted before you get to a particular objective.
"I think you always should expect to see a healthy tension between elected ministers and officials."
That said, in his experience in the ministry with Brook Barrington as chief executive there had been "an extremely healthy chemistry where there is a respect for professional privileges and prerogatives of each and we get on and get the job done".
One of the great privileges of the job had been to see how well some ambassadors represented New Zealand in difficult places overseas.
"I think the ministry should be very proud of its capacities and achievements."
At a farewell function at MFAT last week, he was presented with a montage of photos of himself in various countries visited with an inscription: "For a minister who worked to change the world the better."
It may take pride of place in his backbencher's office, perhaps over the current picture, a portrait of McCully in sand presented during a trip to Vietnam several years ago.
He gave his own assessment of his term as Foreign Minister in a recent speech to the Institute of International Affairs in Wellington, but made no mention of the two biggest controversies: a deal to fund an agrihub he got through Cabinet to repair what he calls a "poisoned" relationship he inherited with Saudi Arabia; and Israel's recall of its ambassador after New Zealand co-sponsored a Security Council resolution condemning Israel's continued settlements in the West Bank for undermining the two-state solution.
He remains circumspect on both.
He would not comment on a suggestion that Israel is waiting for him to depart before making any attempt to restore relations.
Nor would he give any details about the blasting he got from Israeli Prime Minister Benjamin Netanyahu in which the Prime Minister reportedly warned McCully it would be a "declaration of war" if he proceeded.
"I don't intend to confirm or deny [that]," he said.
"It was a very memorable and very challenging conversation."
On the Saudi deal, he acknowledged he could have done things better but said the free trade agreement with the Gulf states that had stalled would be signed soon, and he hoped he would get some credit.
"I was travelling around the world more than half the time, working very hard. If there were shortcomings of a cabinet process or a cabinet paper process, it would hardly be surprising but we did the best job we could and we certainly got the result we wanted."
He listed his three career highlights as winning a seat on the UN Security Council with 75 per cent backing of UN countries; rebuilding trust and confidence with the United States to the point that it would feel confident about sending a ship to NZ - it has sent two; and putting more focus on the Pacific.
McCully said the physical demands of the job through constant travel were tough, although he was not complaining. It was a reality.
"Whether you like it or not, the foreign policy world is one where the currency is the official meeting and the official visit and you have to go. You have to be prepared to invest in the relationships and then you get to pick up the phone."
But it meant he was often jet-lagged at the moment he was about to deliver a big speech or have an important meeting.
"You live in absolute fear of making mistakes, when your mind is just not working as sharply as you would want.
"That has been an abiding fear over eight and a half years, that just with the tiredness and the jet-lag that you'll be asked the wrong question at the wrong moment or you'll say the wrong thing.
"You have got to try and manage yourself so you minimise that risk and I've worked very hard to do that."
When he leaves Parliament after the election, he will make himself available to the next Government if it wishes to use the skills and contacts he has built up.
But he does not want a job, and he definitely doe not want a job as a diplomat.
"I've never wanted to be a diplomat. I've constantly been astonished that people speculate that I might, having been Minister of Foreign Affairs, become an ambassador, working for the ministry that I have been minister for. It has never ever been on my mind.
"For a start I want to live in New Zealand."
He is going to have a break but he wants to learn golf, resume flying lessons and see more of his family which includes a 2-year-old grandson.
"I'm going to have a lot more time for personal family things but I'm not going to become a hermit. I'm 64. I've got a few kilometres on the clock but I think the machinery is good for a few kilometres yet ... and hopefully using some of the skills and some of the relationships I built up."
