High Forty had won his previous five starts over the big fences, including the Koral Steeplechase on the opening day of the National carnival.
"This horse has just amazed us this year with the way he has just kept on improving," Anderton said.
Sharing in the National glory was the Cambridge-based jockey Michael Mitchell, who has ridden High Forty six times for five wins and a runner-up finish.
"It's a great feeling and it's brilliant to have a South Island winner," he said. "He's a super horse to ride, he relaxes and jumps so well."
High Forty and Mitchell bided their time off the pace before improving near the rail across the top and then asserted their superiority.
"I attacked down the inside to find the short cuts and he ran away from them," Mitchell said.
High Forty was out by 12 lengths at the post from a brave Mr Mor, who took second off Hezanakilad close to the post. Get Flash was fourth ahead of last year's winner Eric The Viking, who weakened out after making the early running.
Meanwhile Ready Eddie is a two time winner at the Grand National meeting and in 12 months' time he could be back for the main event.
The Awapuni gelding won his maiden on the track in 2013 and he made a successful return to Riccarton yesterday to claim the Speight's Mid Ale Premier Hurdle.
In between times, Ready Eddie has battled injury problems which resulted in a subsequent change of stable from Mark Oulaghan to Laura Knight.
The son of Yamanin Vital is part-owned by Knight's father Gary, a former All Black prop, who also has a share in stablemate Wotabuzz, the 2012 winner of the Grand National Hurdles and next year's feature is the dream goal for Ready Eddie.
He was ridden by Matt Gillies, who guided him to a comfortable two length defeat of Shamal while San Pedro completed a North Island trifecta.
- NZ Racing Desk.