"It's like when you lose your wallet," he says "and your mind just goes blank and you can't hear anything," he told the Weekend Herald this week. "Everything just disappears in your brain - like the plug comes out of the bottom of the sink. It was that sort of feeling."
It's little wonder he was shocked. Top honours for mandarins have been rare in recent decades. Margaret Bazley, made a dame in 1999, was an exception.
Wevers headed the team of public servants who support and advise the Prime Minister and cabinet ministers - as opposed to the Prime Minister's Office which supplies personal and political support. The department acts as the ears and eyes for the PM across the whole of Government.
"You are not there to serve their political interest," says Wevers. "You are there to serve the public interest and to help them to be the most effective Prime Minister they can be."
Wevers' career could have been quite different. His dream of being a professional golfer was a real possibility with a handicap of two. He was also a Wairarapa regional rep.
In 1968, aged 16, he was caddie to the great Bob Charles in a charity match against Australian champion Peter Thomson. (Thomson won, hitting a 67 to Charles' 70 - the par was 72). A picture of the two future knights was recently framed and presented to him by friends.
In the end his mother said it was a decision he had to make himself, and he has had no regrets.
Wevers has worked for three Prime Ministers - Helen Clark, Key and David Lange.
He organised a highly successful Apec summit in Auckland in 1999 when Jenny Shipley was Prime Minister, and was Ambassador to Japan after learning fluent Japanese.
But it was his less visible leadership in the Christchurch earthquake recovery, the reform of the public service and his expertise in foreign affairs for which the Government was especially grateful, Acting Prime Minister Bill English confirmed.
"He has been a problem-solver for two Prime Ministers through an awful lot of problems, particularly in the intelligence and foreign affairs areas."
English cited in particular Wevers' role in "reframing" the relationship with the United States, and over the emerging threat of terrorism "where a lot of it is about judgment and not overreacting."
Wevers has never forgotten the advice of a former aide to Robert Muldoon and David Lange. "The job of the staff who are closest to the Prime Minister is to create 'a pool of tranquillity' around the Prime Minister because you can't have fuss and flap and tension and yelling going on."
It is something, according to those who worked with him, that he perfected. Nobody can recall him getting even remotely rattled in his time at the Beehive, and his skill in getting people and agencies to work together are now legendary, especially immediately after the earthquake last year. He could be running up to a dozen meetings a day with heads of various agencies summoned to the Beehive over different issues needing co-ordinating.
After the immediate disaster recovery, the wage subsidy policies which would normally take months to prepare was ready within three days. Social service providers found new ways to co-operate as did schools in the worst affected areas.
Wevers sees potential for some long-term changes. "You see some of the innovation in the delivery of public service going on now in Christchurch, forced by necessity. Some of those are possible for perhaps wider roll-out across New Zealand."
English says the public service was it at its best, "grappling with uncertainty and complex and urgent issues but with very professional leadership".
"And in the normal course of events they can forget what they are capable of. But it does take particularly good leadership to achieve that."
English also highly commends Wevers' role in the public sector reform, which is being driven by English.
Wevers was a junior in Lange's office when the last significant reforms took place, including deregulation and the establishment of state-owned enterprises. But then reform slowed down. "We lost the ability to innovate," he says.
He is also supportive of public sector chief executives taking a more public role in encouraging debate on policy, as Treasury Secretary Gabriel Makhlouf controversially did earlier this year over teacher performance and class sizes.
"I think our system should be robust enough to allow that discussion to happen," says Wevers. "You want some more dispassionate discussion of a lot of these issues."
The low point of Wevers' career was the mortifying leak of 2006 when a messenger in his department gave Telecom the cabinet committee paper on Budget plans for deregulation (which wiped $1.8 billion off its capital value overnight).
"Yikes," was his understated response to State Services Commissioner Mark Prebble who phoned him one evening to tell him Michael Ryan had confessed.
Wevers offered his resignation to Helen Clark - although Prebble was his employer. Wevers says he needed to know Clark still had confidence in him. She rejected his resignation and told him "not to be silly".
WEVERS WAS born in the Netherlands to a Dutch father and English mother. He turned 1 on the ship Rangitata en route to New Zealand.
His father was an architecture student. To elude the Nazis, he spent his war in safe houses in German-occupied Holland.
The couple settled in Masterton after Rotary helped get Wevers senior an architecture job. The immigrant family, which grew to five children, was warmly welcomed into the community, Wevers remembers, and his father became the first Dutch borough councillor in New Zealand.
It was a politically aware family but not a party-political family, says Wevers. Debate was encouraged around the family table.
Wevers' connection to the Wairarapa is still strong. A few years ago he and his wife, Lady Louise Rolleston, bought eight acres near Martinborough where they have a cottage and he has planted about 300 trees.
The closest Wevers got to political activism was being treasurer of the Native Forest Action Council in the days when native forests were being cleared for pine plantations and beech trees were being chipped and shipped to Japan for paper.
At Foreign Affairs, one of his most life-changing events happened to him almost by accident. Having demonstrated proficiency for languages in a ministry test using Kurdish, he was offered the chance to learn Chinese or Japanese with a junior posting and was given 24 hours to decide.
He opted for Chinese, only to be told that that opening was gone and so was offered only Japanese.
For two years he and his wife attended a language school in Yokohama, two students to one tutor for six hours every day plus homework in four 12-week terms.
"It was one of the most rewarding things I've ever done. To end up being able to read a newspaper in another script is like going into Alice in Wonderland."
Wevers had two postings to Japan, as a junior, then as ambassador in 1994. Not only was it enriching, as one of the very few ambassadors with professional proficiency it gave him what he calls "unparalleled access". He could ask to see any Japanese official and doors would open.
Sources say he was so proficient in the language he would sometimes correct his Japanese assistants.
Learning Japanese also led indirectly to his first job in the Beehive. Wevers returned to New Zealand in 1985 during his first posting to Japan to act as David Lange's interpreter during the visit of Prime Minister Yasuhiro Nakasone. And Lange asked for him.
Wevers is a strong advocate of language learning, including te reo, and is critical that there is not a national languages policy in secondary schools, for both individual enrichment and in New Zealand's interests.
"Kids who can walk in two worlds I think end up with a much richer world view."
The end of Wevers' duties at DPMC will allow him more time to spend with his wife. She was diagnosed with MS during the second Japan posting and is now in a wheelchair.
But he says, at age 60, he has not actually retired. He doesn't know what he is going to do and won't make any decisions until next year.
There are murmurings that he would be ideally placed to pick up the pieces at Foreign Affairs which is undergoing a bruising restructuring.
But he has twice before sought the top job there, in 2002 when Simon Murdoch got it, and in 2009 when the incumbent and private sector executive John Allen was favoured by Foreign Minister Murray McCully.
The five-year term of State Services Commissioner Iain Rennie is up next year but Wevers deflects talk about that.
"I'm not sure that I want a big full-time job. I suspect the PM has some thoughts. He has muttered about that from time to time. I don't know what they are. But I might do something else.
"I don't have to do anything at all. I could just play golf."
