"However prepared you think you might be, the emotional shock is immense," Sir Douglas says. "I found for three weeks I was very emotional, weepy. My wife (Barbara) suffered. She got shingles, she got heart palpitations."
Barbara is younger than Sir Douglas and all of a sudden had to start thinking about life without him.
"It's a very complex time. It's hard to go to sleep when you think you're facing the end of your life."
Roll forward four months and Sir Douglas is a man more at peace than distressed. He is undergoing aggressive chemotherapy, which at his age - he turned 75 this week - his body is tolerating well. Apart from annoying shingles and tiredness, he can't complain too much.
His specialist told him his body is handling the chemo well. "So he ratcheted up the amount he's given me, which he's pleased with."
Given his enormous wealth, what would Myers swap right now for a clean bill of health?
"Nothing, not at my age. I'm 75."
Having plenty of dosh came in handy when engaging oncologists and specialists at a private London clinic. The chemotherapy Myers is on is costing hundreds of thousands of dollars and is not funded by the National Health. With a bit of luck, it will buy him more time.
Since chemo started, a scan has showed two of the tumours have disappeared. The rest have shrunk by 50 to 70 per cent. That means he can still keep reading the obituaries but he can also use the word "hope".
"The issue of hope is a hell of a lot greater than it would have been 10, 15, 20 years ago. And in another 10 years it'll be that much greater again. If you go to someone as good as you can get, there is stuff but it is very expensive."
He's had seven of his fortnightly treatments and is negotiating with his oncologist for a few weeks' break in the summer to be in New Zealand for the marriage of his son Campbell to his American fiancee Audrey Smith. The wedding is planned for New Year's Eve at Kauri Cliffs, near Matauri Bay, and not far from the Myers' family farm and 1970s-style beach house, a place Sir Douglas visits every summer.
Apart from concentrating on getting through his treatment, he's been reflecting on his life and what matters now. After the shocking July diagnosis, he wasn't sure where his three children - Jessica, Laura and Campbell - were. All were travelling and it was some time before he could tell them. All families have little tensions, he says, but as soon as they heard the news they forgot "the little petty crap" and rallied round.
"Maybe it caused them to think about their own lives. That's why you talk, that's why I'm talking, so people can have a think about these things."
His former wife, Stephanie, the mother of his children, came to England and stayed in the family home for three weeks.
"We had dinner outside every night. It was beautiful for weeks on end, had big fires and talked and reminisced, a few friends came round. It was as pleasant a few weeks as I've ever had."
That and contact from old friends have buoyed him. When talking about those people from his past, his voice cracks slightly with emotion.
"People write to you that you haven't seen for 40 or 50 years. That's how my life was constructed, a series of contacts with people who influenced me. If anyone can be bothered to write to me I'll certainly bother to express my own feelings."
And he's kept it up. Some of the correspondence has become frequent exchanges.
As Sir Douglas points out, if he'd dropped dead of a heart attack - "which at my age is the alternative" - he'd have missed out on all that.
Now he's ready for whatever is ahead. He told his doctor he's stared death in the face and is relaxed about it. In Sir Douglas-style reverse psychology, he thinks if he's relaxed about dying then he'll do his best not to.
Sir Douglas has been writing lists about the good things happening. He jokes he no longer has to worry about his weight. He's the lightest he's been since he was at school. And he can sleep in the afternoon, and then again at night, no problem.
And he's still having fun. He sold his luxury superyacht Senses. That's freed up time to try other things. This year he's been in New York with his son, fishing in Alaska, flew to Burgundy with friends to visit vineyards and then down to Tahiti to go fishing with Marlon Brando's son.
In March this year he was in New Zealand to select this year's Myers Scholar, former Hamilton Boys' High School economics scholar Thomas Simpson, who is now studying at Caius College, Cambridge.
Sir Douglas also spends several hours a day at his offices either in the country house or in London. From his London apartment he can see daughters Laura and Jessica, the mother of his four grandchildren, who live in London.
From there he can still be a proud Kiwi, hearing of the Man Booker Prize success of novelist Eleanor Catton, or Team New Zealand's performance in San Francisco. "The All Blacks are here in a couple of weeks," he says, with pleasure.
Sir Douglas is pleased to hear Auckland has been voted one of the top 10 places in the world to visit by Lonely Planet. And, for the first time in "quite a long time" his family company has invested in New Zealand, in the dairy industry.
He thinks New Zealand is a "happier" place these days, is chuffed about his knighthood (New Year's Honours 2010), is glad to see the back of Helen Clark and wouldn't mind having dinner with John Key because he thinks he's "a nice man".
It's been a busy year for his company. There's Downtown Music, a recording studio in New York - Gnarls Barkley's hit song Crazy was its first success - and now a music publishing business. The company has just done a deal with Yoko Ono to secure the rights to all John Lennon's music after The Beatles.
Myers has also invested in a device that stops tables in restaurants from wobbling, no doubt something that has irritated him over the years.
And he has invested in a company that tests drugs for pharmaceutical companies. "They (the drug companies) are not allowed to do it themselves. I suppose because they might cheat, so they have to farm it out to companies like this one."
A third of the company's business is oncology - a coincidence, he says, but a happy one.
As the interview winds up Sir Douglas becomes reflective again. He has a message: "If you get a bit of a shock, it's quite a good rain check to just take stock of yourself, your life, what you're doing, the people you like, the people you don't like, things you believe in and, if you're lucky enough to get an extension, you are better for it. Life's not fair and you need to accept it and get on with it. And do the best with the hand you've been dealt."
