The talented stayer turned jumper has been a revelation since switching vocation and is one of a number of Kiwi gallopers towards the top of the market in the Grand National Hurdle (4200m) at Sandown this weekend.
Fellow New Zealand jumper Tallyho Twinkletoe will have to create a modern day weight carrying record if he is to record a second win in the Grand National Hurdle, lumped with a 73.5kg impost, three kilograms more than Gobstopper, who chased him home into third last start.
Campbell retains a share in Gobstopper, having prepared him to win last year's Brendan Drechsler Hurdle (3500m) before failing in the Grand National Hurdle and subsequently leaving him with Victorian jumps trainer Eric Musgrove.
The son of Tavistock has won three feature hurdles this winter with wins in the Galleywood Hurdle (3200m), Australian Hurdle (3900m) and Kevin Lafferty Hurdle (3200m) and will face his biggest challenge to date on Sunday.
"Eric seems happy enough with him and he ran well last start," Campbell said. "It was a good field and he went a nice race but his main aim all along has been the Grand National.
"I'm hoping there's a little bit of petrol left in the tank.
"He was new at the game this time last year when he failed in the Grand National and he's got some ringcraft now so it will be interesting to see how he goes."
Gobstopper has won in excess of $500,000 in career prizemoney and Campbell's decision to leave the horse across the Tasman would be further vindicated should he land the lion's share of the A$250,000 purse on Sunday.
"I got bagged a bit for leaving him over there but it's the best thing we ever did," Campbell said. "He's won three $100,000 races."
Campbell expects to be tuning in to Australian racing on a more regular basis after recently sending some handy types across the Tasman, with the blessing of principal owner Tommy Heptinstall, who is these days based in Melbourne.
"Preakness and Wertheimer have gone to Trent Busuttin and Natalie Young in Victoria and Trident, Talamo and Vladivostok have joined Michael Hickmott," Campbell said. "Michael also has Aqueduct, Peloton and Tibetan who went over a bit earlier.
"Probably the better two have gone to Trent and Natalie because we think they will make the grade in Melbourne and the ones that have gone to Michael in South Australia are a cheaper option to have them trained, yet still running for great money and if they're good enough they can race in Melbourne.
"We have done it with New Zealand racing up in the air a bit and the stakes are poor.
"We're testing the waters over there and we've got two very good trainers. If it works, great."
Despite losing a number of his better two and three-year-olds, Campbell believes he has some quality yearlings, rising two coming through the system."I've still got nine rising two-year-olds here, so I've still got plenty of horses and we'll never send two-year-olds to Aussie as it is hard to compete with their focus on younger horses and we can give them the perfect grounding here."