Andrew Nicholson and Avebury, who were second in the CIC*** at Blenheim.
Nicholson, on Mr Cruise Control, added only a handful of time penalties on the cross-country to his dressage score, but the dropped rail in the final phase meant he missed second place and had to instead settle for fifth.
Lucy Wiegersma and Granntevka Prince kept their cool in a nail-biting finale to claim the three-star title. "It is very gratifying to win an event of this stature, especially on a fantastic young horse like Prince," said Wiegersma, whose next stop will be the European Championships in Fontainebleau, France next week with Woodfalls Inigo Jones.
"Emily and Drivetime wouldn't be the ones you want sitting right behind you going into the show jumping as they consistently jump well," said Wiegersma, who was delighted with how the nine-year-old went throughout the event.
Emily Baldwin and Drivetime remained in second place from start to finish. Eight time penalties on the cross country and a pole down in the show jumping hampered the chance of any rise up the leaderboard.
"I was disappointed to have a fence down as he is usually a very good jumper, but I was a bit slow to the parallel and he just had the back rail down," said Baldwin, who won the CIC*** classes at both Belton and Hartpury earlier this year.
Izzy Taylor, from Aynho, made a meteoric rise after the dressage, moving from 31st to third place riding the Honourable Mrs Lorna Schuster's homebred mare, Briarlands Matilda. She was also presented with the Marlborough trophy for the highest placed rider who lives within 50 miles of Blenheim Palace.
Taylor added nothing to a dressage score of 53.9. The only other person to keep a clean sheet throughout the competition was Melanie Wilder who climbed from 33rd to sixth place during the course of the competition.
"Briarlands Matilda is a class horse. She's brave but careful with it," said Taylor of the nine-year-old mare, who was competing in only her second three day event - the horse was second at Hartpury CCI** last year.
In fourth place was Daisy Dick and Spring Along, on 54 penalties.
Two rails were the undoing of most of the remaining Kiwi contingent. Mark Todd and Land Vision dropped two to finish in 14th place on 64.6 penalties. Joe Meyer and Sanskrit were close behind, in 16th place on 65.9 penalties, after adding 6 faults in the jumping. Craig Nicolai and Just Ironic also had two down, to end in 20th on 72.8 penalties. Caroline Powell and Boston Two Tip also dropped two rails, to finish in 46th place on 127.4.
Alex Hua Tian, 19, was the highest placed rider age 25 or under. He was awarded the £250 in vouchers from the Horse Trials Support Group. He was the only rider to represent China in the eventing at the Olympics in Beijing last year.
Claire Boumphrey received a top hat from Patey for climbing the most places after dressage. She moved up from 74th to eventual 27th place after adding just 10.4 cross country time penalties to her dressage mark.
• Piggy French has won the inaugural CIC*** class for eight and nine-year-olds, on Flying Machine. Adding just one time penalty in the show jumping to her dressage score of 45.2, she managed to stay 0.3 of a penalty ahead of Andrew Nicholson and Avebury.
Flying Machine, who was making his debut at three-star level, was the British Eventing five-year-old champion in 2006 when ridden by Leonard Goerens. Owned by Anne Marling, Belinda Keir and Sue Wilkinson, the nine-year-old gelding by Cult Hero has shown consistent form with Piggy. He has finished in the top ten at every event he started this season, including winning Barbury CIC** in July.
Avebury was foot perfect throughout, adding nothing to his dressage score of 46.5. The grey gelding won the Saumur CCI*** in the spring and is owned by Rosemary Barlow, who is a stalwart fund-raiser for the Horse Trials Support Group.
Nicholson was also eighth on Oplitas, on 58 penalties.
Oliver Townend, the dressage leader, had one pole down and two time penalties in the show jumping to drop him to sixth place, but a faultless cross country round aboard ODT Master Rose propelled him back up the leaderboard and into third place.
Caroline Powell and Boston Two Tip.