"It was probably my experience at this level which got me through. Fortunately I had been doing a lot of crossfit work in the gym," said Vallance, who scored his team's final try in the final.
He got the call when Havelock coach Murdoch Paewai learned that Hawke's Bay Sevens captain Adam Bradey couldn't play because of an injury and fellow Hawke's Bay Sevens representatives Ihaia West and Isaac Paewai were unavailable because of a family bereavement. He filled in for the Havelock North premiers in 15s rugby last year, when Magpies commitments and injuries depleted their depth, and he said there was a chance he would be required again this year.
His Sevens form on Saturday suggested the 1999 under-19 World Cup winner, who was once rated ahead of All Black captain Richie McCaw on the country's loose forward rankings, has at least another Waipukurau tournament in him.
"I keep saying no but I keep coming back. Watch this space," Vallance joked before joining his team's victory celebrations.
There were two key moments in Havelock's final win, both in the second half. The first was a try-saving tackle that speedster Shannon Chase made on Michael Ruru, and the second was an 80m runaway try from Levi Armstrong which put the defending champions 19-7 ahead.
Men's player of the tournament, Gillies Kaka, again displayed his class for Havelock North while Ruru, Star Timu and former Magpies No8 Peniasi Tokacece were consistent performers for Tawa.
Havelock North were also unbeaten on the way to winning the Colts A-grade title. They beat another Napier Boys' High School-dominated team, Napier Pirate Rugby and Sports A, 26-0 in the final.
Havelock North's Trinity Spooner deserved his Colts award for player of the tournament after displaying the benefits of his time in the Hawke's Bay men's squad and a training camp with New Zealand Sevens coach Gordon Tietjens.
Manawatu's Kia Toa denied Havelock North a clean sweep of the three major titles with a 12-0 win in the women's final. Kia Toa's superior structure and cohesion proved the difference between the two sides.
However, Havelock North did well to reach the final considering the calibre of the other sides and the limited time the Havelock players - including Netherlands import, 2011 IRB Women's Sevens player of the year Kelly van Harskamp - had together in the build-up to the event. Along with Van Harskamp, Kate Bradshaw and speedster Candis Cardie were prominent for Havelock North.
Gutsy Napier Pirate Rugby and Sports player Krysten Duffill won the women's player of the tournament award.