Referee Alistair Kalin ruled no try for New Plymouth at the 12-minute mark but two minutes later the home team scored through tighthead prop Perry Solomon.
Parker’s conversion made it 10-0.
From an attacking scrum midfield on the 22-metre line, three minutes before the break, New Plymouth right wing Matua Robinson came off a great pass from fullback Mason Milham to score the first of his two tries for a 15-0 halftime lead.
Gisborne loosehead prop Amanaki Tonga scored a try in the 47th minute.
A tap-penalty by halfback Nic Proffit five metres from the hosts’ goal-line resulted in four phases of play to put Tonga within striking distance.
The conversion attempt missed and New Plymouth led 15-5.
Both forward packs had their moments. For New Plymouth, loosehead prop Shaun Leath had a strong all-round game.
After 62 minutes, Gisborne turned the ball over 10m short of halfway and right wing Matua Robinson went in for New Plymouth’s third try . . . 20-5.
Reserve openside flanker Tom Simson scored in the 61st minute.
Parker converted the try to end the scoring.
Gisborne Boys’ High head coach Mark Jefferson said his side struggled at the contact area and “just to get into the game” in the first half.
“Our ball presentation then was such that we turned it over and struggled to build momentum,” he said.
“The boys played much better rugby in the second half.”
The second 15 outscored New Plymouth by four tries to three and came from 14-12 down at halftime to win at McNaught Field.
Gisborne tighthead prop Isaiah Kiwara opened the scoring with the first of his two first-half tries. Fullback John Horua converted the second.
New Plymouth’s first-half tryscorers were openside flanker Rodney Meredith and halfback Topia Barrowcliffe, their tries being converted by right wing and MVP (most valuable player) Tom Cutler.
New Plymouth centre Noah Callaghan scored in a second half in which Gisborne first-five Bryan Howard and reserve left wing Jacob Wyllie both scored.
Horua, Gisborne Boys’ High MVP, finished with a penalty goal and three conversions.
New Plymouth second 15 assistant coach Darryl Leath said the teams were evenly matched and showed some outstanding interplay.
“The Gisborne forwards were the difference,” he said.
“They played with a lot of passion in the second half.”
Gisborne coach Graeme Newlands said: “This win, our success, rests with a core group of boys who have stuck with the team, played their guts out and stepped up to play for each other. They all showed outstanding commitment.”