The new book, I'm in a United State, explores Henry's relationship with the United States, touching on everything from weddings, politics, road trips and Covid-19 lockdown.
"This book sets out to establish why I love the United States. It's written in real time, it's got road trips in there and just a lot about me which I haven't printed in previous books," Henry said.
The book is Henry's third, after spending his years off New Zealand screens travelling and writing the first two. Henry currently splits his time between New Zealand, his yacht Olive, and his home in Palm Springs.
"I live there probably about five months of the year. This year might be fractionally less, about four months, and when I'm not there I just miss it so much. I'm only prepared to do two weeks of quarantine a year."
While in Whanganui, Henry reminisced on one of his fondest memories of the city.
"I used to come here and there was a bed and breakfast on the side of the Whanganui River. Huge, huge mansion of a house and you'd have dinner there and they'd actually rode a full size horse into the house.
"It was like it was an earthquake. There was this thundering noise and here was this horse with a guy in all his gear dressed up on the back of it."
Asked if viewers can ever expect a return to our screens, Henry said he was happy in his retirement.
"I've been offered some things and I've done a bit of work recently. My retirement plan was to spend time on my boat, but those plans have changed a bit. I just want to retire really.
"Never say never, but I pretty much have said never."