Victoria Seymour loved a glass of bubbles. So when the 50-year-old chief pharmacist of Northland DHB found herself feeling yet again like she couldn't stomach a glass of wine, she knew there was "something wrong".

The devoted mum-of-three stopped off at the chemist to get a pregnancy test, which subsequently turned positive.

But, as a scientist – and knowing she couldn't be pregnant – it confirmed her hunch that something more sinister, a tumour, was giving her a false positive result.

Five months later, just before succumbing to liver cancer, Vicki asked one request of her younger sister Nicola Faithfull and her best friend from primary school Penny Swarbrick: "Please look after my boys."

And while nothing could have prepared him for the grief of losing a parent in his early 20s, politician David Seymour is grateful that his dear mum thought to provide solace in her absence for him and his two younger brothers, Mark and Xander.

As he introduces his "surrogate mothers" to the Weekly, the 38-year-old Act leader sums up their special relationship – they feed him, inspire him, keep his feet on the ground and always have his back.

He explains: "It's been a beautiful thing to see how they've covered for their best friend. I can go to them for any sort of advice."

"And sometimes he gets it for free!" quips Penny, a lawyer (and no relation to Green party MP Chlöe Swarbrick).

"Well, I don't really ask for it, I just receive it," grins David, who enjoys hilarious banter with them throughout the interview.

Both women also came to the first episode of Dancing with the Stars to support him when they assumed he'd be the first contestant to get voted off.

"Yeah, that was really touching," he deadpans. "In fact, they said Mum was a better dancer than me, despite her having had polio.

"They've also been very good at feeding me because, as you can see, it's not something I always remember to do myself."

Penny, 63, and Nicola, 59, often receive cheeky text messages during the weekend from David asking: "Is the kitchen open tonight?"

"After David came back from his time working in Canada, he stayed with me and ran his first Epsom political campaign and got elected," recalls Penny, who is also his godmother.

"But I knew he'd probably be eating junk in Wellington from Monday to Friday, so I told him come to mine for a roast on Sunday nights so I knew he'd be getting at least one good meal a week.

"My own two sons were both overseas and I had recently been widowed, so it was lovely to have his company. Then other youngsters David's age heard about this free Sunday roast and suddenly we had this diverse group here every week, and it was great.

"It was basically the SPCA of Epsom!" says David.

As a child growing up in Whangārei, David says Nicola was always "the cool aunty".

"She lived in London and had enough disposable income at the time to bring us the best toys. Then when I went to boarding school in Auckland, both Penny and Nicola lived there, so I started to see a lot more of them from then.

"When I started my first door-knocking campaign of 14,000 houses, Nicola helped me. She was very fit and I just remember thinking I must keep ahead of Aunty!"

Their unwavering support has helped take the sting out of his mum never seeing him become an MP or Act leader.

Today, as he sits cross-legged on Penny's couch during our chat, David remembers back to that harrowing time in 2007 when Vicki was dying. He was 24 and about to move to Canada to work as a policy analyst.

"Mum said to me, 'You've got to still go! Just come back for my funeral,' thinking she had weeks left. But then she died two days later. It was very shocking," he recalls.

"My mum was the most powerful influence in my life. As one of the last people in the Western world to contract polio as a baby, she was told she would not walk, work, go to university, drive or have children.

"And, of course, she defied predictions to do all those things and showed me you can overcome anything if you are determined to. She was even the first person to get a Masters in Pharmacy. I liked to call her Northland's biggest drug dealer."

He finds himself often thinking about what it must have been like for Vicki to grow up disabled in the '60s.

"Now we have a much more enlightened view, but back then disabled people were almost shunned. Mum was determined almost not to acknowledge it, even though she couldn't walk that well.

"She spent at least one year away at the Duncan Hospital for polio victims in Whanganui and another at the Wilson Home in Takapuna. But she never once complained or referred to her disability.

Adds Nicola: "Because Vicki did all these things that everyone said she couldn't do, when she was diagnosed with cancer, we all thought, 'Oh, she'll conquer that too', because that's what she's always done."

Before her death, Vicki recorded a DVD message for each of her three sons' future partners.

David, currently single, hasn't watched it yet, but says it was a good example of her forward planning and always thinking of other people.

Project manager Nicola muses that he takes after his mother too.

"He has Vicki's determination, intellect and amazing work ethic. She was committed to anything she did, so when she had children, it was all about them. David's invested in family, too. He used to take his small cousins down to the park for me, but later said it was only because it helped him be a chick magnet," she smiles.

"When Vicki said to me, as she lay dying, 'Look after my boys', it was easy to answer yes," tells Nicola, getting teary-eyed.

"And Nicola has really done that, as has Penny," says David.

"The way they've shaped me, and Mum as well, is that they're part of the vanguard of women who were the first to make it to the top of their professions. It's had a really big impact in that I'm probably the first of a generation who don't really see gender, I just see people."

He says that as a former electrical engineer who's prone to thinking "entirely in numbers", the women have probably helped "humanise" him a bit too.

"There's a danger that all politicians get intoxicated by power, so I'm just really lucky that Nicola and Penny are such a positive influence. These guys keep me extremely grounded."
"Oh, that's the nicest thing he's ever said," jokes Nicola.

"Well, these women are quite honest with me," he says. "A lot of politicians can get very out of touch the longer their career goes on or they stop taking advice, but I don't have that option with these two!"