Graham Norton doesn't think he's drinking more during the pandemic - he's just noticing now how much wine he actually gets through a night.

"If people are coming around, you kind of think, 'Wow, they really drank a lot, they were some booze hounds in last night,'" he told Mike Hosking.

"But when it's just you, when those cases of wine are empty, you're like, 'I wonder where that wine went?'

"It doesn't take Jessica Fletcher to figure out where the wine went - it went in my big gob."

The celebrated talk show host likely has plenty of his own wine to work his way through, after signing off a new blend with his New Zealand-based Invivo wine label co-founders Tim Lightbourne and Rob Cameron.

And Norton has a lot to celebrate: The trio is celebrating reaching sales of 10 million bottles of Graham Norton wines, on the heels of the release of Norton's newest book, Home Stretch.

Norton marked the milestone on Instagram with a picture of a Zoom call tasting with Lightbourne and Cameron, telling his followers he didn't drink all 10 million.

Back on the screen to chat to Newstalk ZB host Hosking, Norton said he's cut down on the drink after a boozy stint in Ireland.

"Now I'm back in London, in work mode. Now I'm limiting myself to two drinks a night - unless I don't," he said.

Norton said he understood why people abstained from alcohol for health reasons.

"But if you're just doing it for its own sake - really?

"Look, if bits of you start falling off, then maybe something went wrong. But if it's not affecting your work and you're not ill, then why not?

"I mean, we've got to do something."

Norton's recently released fifth book begins with tragedy: A car-full of youngsters crashes and the three who survive are forever scarred by the experience.

His previous novels, Holding and A Keeper, are both bestsellers, with the latest book based in his home country Ireland in the late 1980s.

Norton told Hosking that writing, for him, sat in a creative sweet spot sandwiched between his television show and radio work.

"I enjoy it as much as I do because it's in such contrast to everything else I do in my career," he said.

"All my other jobs involve meetings. It's creative, but it's slightly creative by committee.

"But there is something delicious, then, about being alone and no one has a say - I am the driving force and the solo author of these books."

Norton is no stranger to Covid-anxiety either, saying the first months of the pandemic felt like someone was sitting on his chest.

"I was lucky, because I was still sort of working. I was doing a version of the TV show, I was still doing the radio show, I was finishing off this book, I was busy."

But he noticed friends with more transient work, or with no work, found the experience much tougher, not only financially, he said.

"I also avoided the news," Norton told Hosking.

"Once I heard that I was supposed to socially distance and wash my hands, that was it. I stopped with the news, there was no news."

He did, however, manage to carve out some virtual working time with his Kiwi wine colleagues Lightbourne and Cameron to decide on next season's GN Sauvignon Blanc's blend.

Every year since 2014, the Invivo wine co-founders have travelled to meet with Norton to taste the latest harvest and sign off the blend over a few hours' tasting.

"This year we had to work virtually with Graham due to international travel restrictions and we couriered six samples of sauvignon blanc from Marlborough to his holiday home in West Cork, Ireland," Lightbourne said.

To bring the virtual tasting to life for Norton, just before Auckland's level 3 lockdown, the boys based themselves up in the Sugar Club atop the Sky Tower for the Zoom call to show him early morning Auckland in the background, they say he loved it from night-time Ireland.

Two hours later, the trio had decided next season's blend of GN Sauvignon Blanc.