He's survived bigger seismic shocks politically and after 26 years in Parliament and one badly failed attempt to be elected Prime Minister in 2002, he has made it to the top job.
Wife Mary says it has been a special day. All six of the English children had come to Wellington for it.
Three are now in Australia, another is heading off on an OE next year, one will be at university in Dunedin and the youngest, Xavier, still lives at home.
English has said the reason he rebuilt his political career after 2002 was to set an example for his children.
"It means a lot to them because it is a great honour for anyone to become the PM of New Zealand. They've watched their Dad work very, very hard. And they really appreciate the fact he has actually been able to achieve what he has been able to achieve even before today. Today is just the icing on the cake."
They are not expecting any of their children to get the same attention as Max Key for their social media antics.
"I wouldn't think so, no," English says and laughs. "I've asked them that and they've said 'that's unlikely.' But I hope they're able to conduct the social media communication that normal kids have."
Mary is yet to assess how her own life will change, but intends to keep her GP practice running and will still "be a mum".
Bill English is usually in charge of the scrambled eggs on a Saturday but Mary may have to fend for herself a bit more.
English was told of Key's decision back in September to give him time to decide whether he wanted to take on the risk of the leadership again. It involved talks with the family and "encouragement from the Prime Minister".
"The whole week has been very positive so I think it has confirmed it was the right decision to go ahead."
And English is straight down to business. He's just chaired his first Cabinet meeting as Prime Minister and all he says of that is "Cabinet is back to business".
But he's clearly still getting use to the title. At one point, he refers to Key as "Prime Minister".
