Thirteen years later he is still here. But speculation he would leave by 2017 has circled for some time and only increased after the health scare that took him out of action for three months at the end of last year. In November, McCully required major surgery to remove a tumour. It was found to be benign, but he contracted an infection and then the MRSA superbug, which can be deadly. He spent the rest of the year on medical leave.
McCully says health was not an issue in his decision and the doctors had given him the all-clear. "But it would be fair to say it was a wake-up call. And it makes you think about your life and perspective. I do want to do some things when I leave politics, so getting carted out with my boots on didn't seem like a very attractive option at the time and it doesn't seem like a very attractive option now."
McCully says John Key encouraged him to stick around and he would like to stay in the job, "with obvious caveats, like how well things are going, how my health holds up, that kind of thing".
As for speculation he will go for the role of chairman of World Rugby (formerly the International Rugby Board) in May, McCully says the first time it occurred to him was when he read the speculation. "And my immediate reaction was 'how much does it pay?' It sounded pretty good to me." He laughs.
"But no, I've had no interest in doing something like that."
He does plan to stay in New Zealand and rules out working as an ambassador for his successor.
The other place the well-travelled McCully does not want to go is back into Opposition.
"It's a long, slow, soul-destroying grind spending nine years in Opposition and if I'd been asked at the outset to sign up for nine years of it I might have made a very different decision."
It was during National's time in Opposition from 1999 to 2008 that he cemented a reputation as an influential backroom strategist, variously dubbed the "Black Prince" or McCullyavelli. Even he does not bother to deny there was some justification for this, beyond a tongue-in-cheek "I'm very much misunderstood".
But his reputation means there are a lot of things he apparently cannot talk about. In Opposition he was credited with engineering the downfall of Jenny Shipley and installing Bill English as leader.
After the 2002 drubbing, McCully became close to the next leader, Don Brash, who wrote in his memoir that McCully had been a confidant but now didn't return his calls.
Others he fell out with during those days in Opposition include Maurice Williamson, David Carter, Nick Smith and Bill English, although the balm of Government has soothed some wounds.
He will not talk about any of this. He has retained his political nose for what looks bad - the reimbursement of a $700 alcohol bill in PNG in the latest credit card expenses show this.
But since 2008 there have only been glimpses of his true Black Prince abilities - he was credited with luring former Labour MP Shane Jones to become an ambassador in what some believed was a cunning plan to neutralise Jones' vote-catching potential.
Since 2008 that side of him has waned - he is overseas too much and National in government has been stable enough not to require his type of alchemy.
McCully gives his time as Foreign Minister as the high point of his career, in particular winning the seat on the Security Council.
But his term has been equally marked by controversy. He changed the old power structure at the Ministry of Foreign Affairs and Trade, promoting diplomats on what he called merit but others called patronage rather than seniority.
The most striking was the appointment of John Allen - the chief executive of NZ Post - rather than a senior diplomat to head Mfat. Allen came in, dragged the kicking and screaming diplomats through a restructure and left, putting the ministry back into the hands of a senior diplomat - Brook Barrington.
It was that department, under Allen, which oversaw the shambolic handling of the Mohammed Rizalman case. The 38-year-old Malaysian diplomat was allowed to leave New Zealand despite facing a serious sexual assault charge.
Labour's Phil Goff, a former Foreign Minister, gives McCully a mixed report. Goff was highly critical of McCully's changes to the ministry and says it is only now starting to recover. "I think he took an organisation that was functioning well and made it dysfunctional."
He also describes the decision to give an $11 million sheep farm to Saudi Arabian businessman Hamood Al Khalaf as "shonky".
However, he gives McCully credit for hard work and for bringing home the campaign to get New Zealand on the Security Council, a campaign Labour started in the 2000s.
McCully's decision not to stand in East Coast Bays comes before the completion of the Auditor-General's probe into that agri-hub on al-Khalaf's land. McCully has previously described it as an attempt to appease Saudi Arabia's anger over a ban on shipping live sheep, prevent legal action and ease the way to a free trade deal.
He says the looming report was not a factor in the timing of his decision. He had not seen a draft and had no inkling of its findings. He is not worried. "I'm going to wait and see what's in the report before talking about it, but I'm very comfortable with the decisions I made."
He says he simply wanted to allow time for a new candidate in East Coast Bays to get established. McCully won the seat by 15,000 votes in 2014 but says that does not mean it is "safe."
"I wouldn't want to be in the position where after 30 years of being the local MP my legacy was to see the seat lost by my successor."
The Conservative Party's Colin Craig stood there in 2014 and there was some talk National would do a deal. McCully adds this to the list of things he cannot talk about.
He also refuses to talk about his personal life. He split with long-term partner, Listener columnist Jane Clifton, some years ago and she has since married Labour's Trevor Mallard.
The gossip pages reported a relationship of sorts with former Silver Fern April Ieremia in 2010. He says these are "as Winston Peters would say, baseless allegations".
He names Paula Bennett as a friend. She worked as his electorate agent in the late 1990s and now sits at the Cabinet table with him. Bennett says she is friends with McCully but does not claim to be a protege of his.
"I wouldn't call him a mentor. In fact, I would say our politics would differ in a lot of areas."
McCully has a reputation among staff as well as officials as a hard taskmaster and Bennett says that was always the case.
"He was a hard man back then, which won't surprise anyone who knew him."
"He wasn't shy in his feedback, that's for sure. But it's because he had high standards and he knew what he wanted and he demanded it of you when you worked for him."
He is infamously intolerant with officials and staff.
In 1999 he resigned as Minister of Tourism after two Tourism NZ board members were effectively forced to resign and given severance payouts over disagreements with McCully.
That intolerance for what he sees as incompetence flared up again after the debacle of overcrowding and traffic jams on the opening night of the Rugby World Cup in Auckland in 2011.
McCully swept in and announced the Government was taking over control of the waterfront area for the tournament, castigating Auckland Council for dropping the ball.
McCully's ambitions have been rather different from those of other politicians. Bennett is now on the front bench - a place McCully has never inhabited either in Opposition or Government.
"I never felt the need really. It means a lot more to other people and I was very happy for others to be promoted to the front bench. It's not really my focus," he says.
He adds a self-deprecating comment that it was likely none of the leaders he served thought he was good enough anyway "so I thought I'd make my position clear from the beginning to avoid being disappointed".
The respect Key has for McCully rather belies this - Key has consistently defended McCully, works closely with him on foreign affairs and, after McCully's announcement, made it clear he wanted his Foreign Minister to stay on.
Then again, it is commonly held belief no leader is brave enough to move against McCully because he knows where the bodies are hidden. McCully says he is more than happy for the media to perpetuate such a myth.
"I suppose it makes me vaguely more interesting."
Murray Stuart McCully
• Born February 19, 1953 in Whangarei
• First stood for Parliament in 1975
• Credited with engineering the downfall of Jenny Shipley and installing Bill English as party leader
• Became Cabinet Minister under John Key in 2008
• Had a long-term relationship with political columnist Jane Clifton but is otherwise fiercely protective of his private life
• Made a Companion of the New Zealand Order of Merit in 2015 New Year Honours
