A kick ahead was re-gathered by Albert at the breakdown, and he popped the ball to Hamilton to grab a double, and soon after O'Leary broke through tackles on his own 30m to dash deep into the visitor's half and put his skipper away for a hat trick, which O'Leary converted from the sideline.
Thames Valley had not come all this way for a blowout, though, as a succession of tap penalties got them into position for lock Timote Mapuhola to drive over.
Whale took it on himself to extend Whanganui's advantage after a tap kick inside the attacking 15m; smashing through the defence and pulling tacklers with him for 33-14 at halftime.
As tempers flared between the sides, an Albert sin-binning proved costly as reserve BJ Lima was on hand out wide to score after Whanganui's defence had held midfield.
Then reserve back Dwayne Hughes made a nice offload to catch out the home side down the touchline for winger Younglei Kanongata'a to run in, with Tegg converting both for 33-28 in the 53rd minute.
Play became 14 vs 14 as Thames Valley reserve prop Sanalio Taunauta was binned for a no-arms tackle, but Whanganui couldn't keep numerical advantage after Albert returned as reserve Temesi Murivalu also got a yellow for a high tackle.
Hughes had intercepted a pass inside Whanganui's 22m and his teammates were already celebrating, but they hadn't reckoned on O'Leary running him down despite a 20m head start, with fullback Te Rui Werihana also getting back to save the day.
Whanganui needed something and Whale supplied it - snatching up a loose ruck ball at full speed to dash through the line and carry it one-handed right under the posts.
At 40-28 and back to 15 players, Whanganui made the game safe by putting together multiple phases from inside their half to make the tryline, where Albert delayed his pass perfectly for O'Leary to run through and score.
There was just enough time left for Thames Valley to throw the ball around and dash 70m for Tegg to score.
Whanganui Development XV 45 (A Hamilton 3, B Whale 2, J Devine, J O'Leary tries; O'Leary 5 con) bt Thames Valley Emerging Players 33 (B McKeown, T Mapuhola, B Lima, Y Kanongata'a, J Tegg tries; McKeown 2 con, Tegg 2 con). HT: 33-14.
Around the grounds
UNDER 15: Whanganui High School U15 also won their school championship, but only just after the WRFU final against Cullinane College U15 on Wednesday. Hosting the game in wet conditions at WHS, the home side scored the game's first try, and so were awarded the title when the scores were deadlocked 12-12 at fulltime.
HURRICANES: It was a tough start for the Heartland Hurricanes U20's to their Youth Council Central Region tournament at Massey University. They lost 69-19 to Wellington U19 last week and 61-8 to Manawatu U19 on Saturday. Whanganui's Ezra Malo captains the side from first-five, while Dillon Adrole is second-five and Rangi Kui a backs reserve.
