Bill English possesses the calmness and experience that guided the country through choppy financial waters - and he's also a dab hand at manning a nappy bucket.

That's the message from a new promotional video released by the National Party, which also uses former John Key to sing English's praises.

With Labour surging ahead in recent polls under Jacinda Ardern the new video seeks to highlight English's experience but also reveal more about his family life.

English recalls being the 10th of 12 siblings and being brought up on a farm, as photographs flash on screen, of him as a child and later shearing sheep.

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Raising six children with wife Mary was at times exhausting, English says, but "the magic of children is something I've always loved".

Mary recalls using cloth nappies when the children were little and her husband was a stay-at-home dad.

"Bill ran the nappy bucket. That was his job."

With polling showing Ardern's strong appeal with women voters the new National video features both Education Minister Nikki Kaye and Deputy Prime Minister Paula Bennett effusively praising their boss.

Another subject is Key, whose shock decision to quit as Prime Minister came with an endorsement of English for leader.

Key notes English's love of rugby, and praises him as providing all-important calmness and leadership during the fallout from the global financial crisis.

Mary English recalls how worried she was when it was clear what her husband, then finance minister, was facing as the country battled its way out of recession.

"I just remember lining up the kids and saying, 'take a long hard look at your father because he's going to look a bit different.' I just thought it would prematurely age him. But I'm happy to say in actual fact he seemed to flourish."