"He could be a bit dopey without them so we put them on to wake him up," said Campbell.
PHOTOS: Best from Cup Day
"But we knew that they could also make him over-race and that would be a very hard way to win a 3200m.
"So we were damned if we did or damned if we didn't but we took the gamble.
"We reckoned while he would take plenty out of himself wearing them, he would also take plenty out of the others."
That proved spot on as Arden Rooney tore down the back straight between the 800m and 400m in a near record sectional of 26.9 seconds, leaving him a sitting duck for the chasing pack.
But that pack were too busy trying to get to Arden Rooney to have any chance of running past him and at the top of the straight only Smolda looked a danger.
His huge run to sit parked after losing valuable field position with an early break was the feature of the race but his brave effort came up a head short after a brutal battle, with Mossdale Conner's manners seeing him trail and get sucked into third.
Before the application of the blinds a month ago Arden Rooney got as long as $26 with the TAB bookies to win today's race but while he may not have been the punter's favourite few could begrudge the first Australian-trained winner since 1987.
He was a cast off, of a kind, from our leading stable of Mark Purdon and Natalie Rasmussen, moving to Manning last January as Australian racing looked easier, Arden Rooney seemingly lacking the speed to beat Adore Me, Christen Me or Terror To Love.
But he has stamina and that was honed to perfection on the torturous Great Western training track used by Manning and Campbell.
"Our track is 2000m of dirt and at one stage rises 12m in the space of 350m," said Campbell.
"So it gets them rock hard fit if they can cop it."
Arden Rooney showed the benefit of the rugged regime when he won the Hunter Cup at massive odds last February but Manning admitted today's win was a level above that.
"I had been here to the New Zealand Cup before and the race, the crowd, everything about it makes it a special day," she said.
"Just to have a starter was something special but to win it is a dream. And to be the first female to drive the winner when it has been going since 1904 is an amazing feeling."
The win takes Arden Rooney past $1million in stakes, much of that will be reinvested back into the New Zealand racing industry as his owners, Merv and Meg Butterworth, are prolific buyers of Kiwi racing stock.
And he looks certain to return next season to defend his title, which would suit Manning just fine.
"That was pretty amazing and we would love to bring him back," she beamed.
"This is his sort of racing he loves, and we to do too."
History Makers
• Kerryn Manning becomes the first female to drive a New Zealand Trotting Cup winner.
• She also trains today's hero Arden Rooney.
• He is the first Australian-trained winner since 1987.
• A gear gamble gave him the zest to win the $750,000 race.