"I knew it could and I knew it should ... but I didn't know it would," he said with a smile.
"I'd seen cities in the United States like Savanna and Charleston which both had a real heritage feel to them and I didn't see why that could not happen here."
But his vision was not shared by the wider populace back then.
"People didn't take it seriously."
However, as time went by, they did, and Napier's unique heritage, born out of disaster in 1931, began to emerge with a passion - to the delight of Mr McGregor.
"I remember the first year we had vintage aircraft arrive - seven tiger moths came over and I watched them and I got quite emotional - quite choked up."
He believes it will continue to grow, but said over the next decade there would have to be a hard look at the accommodation issue as the "no vacancy" signs were part of the big weekend landscape.
"We will need to look at getting people to open their homes up."
Mr McGregor's passion for the weekend, for art deco, and Napier's unique heritage, was undiminished and he said he would continue putting in the time with the trust "until they tell me to go".
Former mayor Barbara Arnott said that while she came into the picture a little later there was always the feeling it was going to get bigger.
"We always said it was like a small snowball that would just keep rolling."
Beginning her role as mayor in 2001, she carried out a presentation centred on art deco which centred on ensuring the people of Napier were aware of their recent heritage and that it was something that needed to be celebrated.
She said it was vital Napier promoted itself as a different sort of city, one able to showcase itself and its unique culture centred around art deco.
So would the snowball continue to roll, gain momentum and grow bigger?
There was no reason why it would not, Mrs Arnott said - but that would be up to the Art Deco Trust and the way Napier embraced it.
It was important there was always a good balance between the various activities that "everyone" could be involved in.
"Success is in its inclusiveness not exclusiveness," she said.
It was about people simply having fun and being able to be part of many things, and that had been happening.
"There aren't many festivals that are so inclusive."
Mrs Arnott said after so many years of attending official events it was relaxing to just wander about.
"I'll put on my best art deco duds and join in the best party in New Zealand."
It is 30 years since people began to look up at the buildings which surrounded them in Napier.
Buildings with all the style and pizzazz from a unique era.
And all built, effectively, along the same lines, as the central business district of the seaside town was put back together in just two years after the shattering 1931 earthquake.
It was a unique architectural landscape, which was not appreciated by everyone as the 1970s evolved as a time when old buildings and fading styles were not seen as relevant.
Some fine old buildings tumbled down, assisted not by earthquake but by demolition hammers.
But in 1985 there was a spark created in the form of a leaflet, titled "Take a Walk Through Art Deco Napier".
The leaflet was funded by the Napier City Council, the then Ministry of Works and Development, and the Hawke's Bay Museum.
It went out to all letterboxes, and a trust had been formed to oversee it - a modest, voluntary, trust.
That was in February, and four months later the trust put its efforts behind the premiere of a television documentary/film created by Peter Wells.
It was The Newest City on the Globe and it was, quite rightly, highly acclaimed.
It was screened at the conclusion of what was the very first official Art Deco walk, which drew those 1100 people to the central city to look at the buildings many had so long simply taken for granted.
Mr McGregor and the late Mary Johnson were instrumental among the small group of people who drove the art deco cause, and the success of that first major outing convinced them there was something special there.
"Mary was incredibly good at monitoring what was happening in the city and finding ways of doing things better," Mr McGregor said in an earlier interview.
"She initiated the art deco morning walks to cater for people who were short of time - which was incredibly successful."
In terms of the walks, back in 1995 3750 people took part in them.
Roll the years through to 2005 and the figure had risen to nearly 19,000.
The following year it moved past 20,000 and today, more than 25,000 people take the walking tours.
It was in 1987 that Mr McGregor was appointed as the first president of the Art Deco Trust which was legally incorporated that year.
It was clearly on the move and in 1992, with the support of the Napier City Council, the trust became a full-time operation with Mr McGregor taking on a salaried position as executive director inside smart premises, which included a small shop, in the old Central Fire Station building in lower Tennyson St.
The attraction was clear, as visitor numbers to Napier, particularly during the big Art Deco Weekend event, steadily grew.
This small city at the bottom of the world had a unique charm, and more and more people wanted to taste that charm.
In a report put together in 2003 it was estimated that the Art Deco Weekend attracted about 8000 visitors and generated about $3.3 million.
By 2010, after running for 25 years, the Art Deco Trust's turnover exceeded $1.5 million, and the numbers who attended last year were put at close to 30,000.
To say it is a major part of the region's tourism economy would be one of the understatements of the year.
Mr McGregor stepped down from his role in March 2008 after 15 years in the driving seat but continues as the trust's heritage consultant.
In June that year, current Napier Labour MP Stuart Nash stepped into the role - at that stage putting his political aspirations aside in favour of spreading the art deco word.
A former director of strategic development at Auckland University, he pursued and gained strong support for the trust.
His links to art deco went back to his father Hal, who was one of the first walk guides.
"Like a lot of kids, when I was in the seventh form (at Napier Boys' High School) I thought Napier was old and boring."
But having left for a time, and then coming home again, he saw the buildings in a new light.
He took an art deco walk of course, and was hooked by what he saw and learned.
"Art deco is something that creates a real pride in the city and it (the big weekend) has become a global event.
As he pointed out, in 2008 it was listed as the only New Zealand destination for Lonely Planet's "must go to" international festivals.
As for the future, it was a case of "onward and upward".
Mr Nash said there were two ways it could go - it could tire and people could drift away, or it could move to the next level, which meant a strong and clear vision of what it would embrace in 10 years - and integrating advancing technology would be one factor to that.
"It is such a great event and such a fantastic celebration of Napier - and we'll be there all dressed up," Mr Nash said.
"Me in my woollen suit sweltering in the sunshine and the kids are dressing up - we love it."
Mr Nash's position at the helm of the Art Deco Trust was only a brief one as he had to resign toward the end of 2008 in the wake of becoming a Labour List MP.
Margot Minett then stepped into the chief executive's role but her stint was not an extended one either.
She began in December 2008 but resigned in September the following year.
The new position of general manager was then created by the trust and in stepped former Hastings District Council marketing manager Sally Jackson who took up her new post in January 2010.
She remains there today, although in a new office after the trust shifted further up Tennyson St.
It has been a busy build-up (again) but it was a sort-of organised chaos at times which was, simply, infectious.
"It's the whole buzz and the excitement and the people - it just all comes together."
