That left the door open for Dee, who relished in the luxury of being the last to go, and made the most of his home-ground advantage.
Despite giving one fence and almighty whack, nothing hit the grass and they came home clear in 49.16 to take the honours.
It was his second win of the show - yesterday Dee rode Merran Hain's Untouchable to victory in the equitation medal class.
Dee says he thought the course would be a tricky and technical one when he walked it before the class.
"It was a very good class . . . and a great start. Ranger (Ombudsman) is not that good at turns but good at covering the ground."
They were the only combination to take a very tight inside turn, which clearly paid dividends.
"I knew I had to do that if I was in with a chance of beating Merrick," said Dee. "This is always a big class and one everyone goes out to win.. It is a real honour to win it ... there are some big names on that trophy."
Thirteen-year-old Ombudsman was bred by Maurice Beatson, and sold to Dee as a 10-year-old.
"I couldn't ask for a better horse," he says.
Last year, the two won the Silver Fern Stakes, and have continued to impress on the national circuit. Dee puts some of that down to time spent in the United States and England in the off-season. Last winter he spent time with celebrated American trainer George Morris.
Dee is hoping to return to the United States next winter, but this time, he will take his horse.
Meanwhile, he is loving having Le Jeune at the Horse of the Year Show..
"It is just amazing to have Philippe here - it is incredible."
Earlier in the day, Le Jeune won the 1.4m class aboard Susie Hayward's stallion Andretti.
Results: Virbac Equine Norwood Gold Cup: Luke Dee (Ocean Beach) Ombudsman 1, Merrick Ubank (Australia) Aladino 2, Philippe Le Jeune (Belgium) Dunstan Kiwi Iron Mark (owned by June Berrington) 3, Mathew Gilmour (Matangi) BMW Leo Silver (owned by Vaughn Jefferis) 4, Catherine Cameron (Cambridge) Campione GNZ 5, Vicki Wilson (Hikurangi) Showtym Cadet MVNZ 6.