"I've enjoyed my job. I've enjoyed every day of the last 44 years. The people of Kaitaia are wonderful. They are good people."
Born and bred in Waiuku, he had arrived in Kaitaia to work with pharmacist Les Gleave in 1973, after five years in Europe then a year or so in Auckland. When Mr Gleave died in 1976 he bought the business, progressively expanding it significantly, and had been there ever since.
The profession had changed beyond all recognition over the years, he said, in terms of bureaucracy. The fundamental concept remained the same, however - to get the right medicine to the right person at the right dose.
"It's a much more complicated process now than it used to be, but the basic principle hasn't changed at all," he said.
Time had passed - 44 years of it - however, and the unrelenting stress that accompanied his chosen profession had begun to take its toll.
"I've been working seven days a week for some time now, and I can't do that for much longer," he added.
"This is a profession that demands precision, obviousl. You need to bring your A game to work every day in this job, and the fact is I'm not getting any younger."
There was a time when he became a little distracted, however - by politics. Mr Shackleton contested the 1999 general election as an independent candidate, and did very well.
"I got thousands of votes from this community. It was quite a thrill. In fact I was the second-highest-polling independent candidate in the country," he said.
He stood again in 2002, as a member of a party that sought to reduce the number of MPs to 99, but to his customers' relief, no doubt, was not successful.
Meanwhile, the Shackleton connection to the pharmacy will by no means be lost. His wife Sandra will continue to work there, as will his qualified pharmacist son Garvin. And it will continue to be Shackleton's Unichem.
Mr Shackleton Snr will continue to enjoy growing the grapes that become Waitapu wines, inland from Ahipara. He will also appear in the pharmacy now and again as a locum, he will continue to serve as a Justice of the Peace, and will continue to be actively involved with Far North Hospice, St John, Switzer Residential Care "and a few other things".
He's even thinking of no longer just talking about fishing but actually giving it a go.