Dave was somewhat forced into training, after struggling with his weight as a jockey. He believed he had two options; to become a taxi driver or to work behind a bar. Fate however, had other ideas. 

Veteran trainer Clarrie Davis, father of Dave’s late wife Marie, was gravely ill. A young Dave O’Sullivan found himself helping around the stable and before he knew it, becoming a horse trainer. Little did he realise, he would go on to be a 12-time champion trainer, stable some of the greatest horses to grace New Zealand turfs and be inducted into the New Zealand Racing Hall of Fame.

Wexford Stables began with Dave O'Sullivan in 1961. It was decided the stable would be named after Dave’s ancestral home in Wexford, Ireland. A few year's later it was confirmed that this was in fact Waterford, although Dave felt it was a little late to change the name. 

Dave's first racedays as a horse trainer were not what you'd refer to as 'smooth sailing.' His debut raceday was fittingly at Matamata Racing Club in 1961. He had one starter, Poetic Justice. Before the race could start, Poetic Justice proceeded to crawl out from the front of his stall at the start barrier - scratched! 

Dave's second raceday as a trainer was at Racing Tauranga. He was confident that his first runner, Abilene, would be his first winner. The horse jumped well, traveled nicely and heading for home, was well in front. As the field straightened Abilene ran across the track, through the outside fence and tragically dropped dead. 

Moments later in the second division of the same race, his unfancied mare, Bridal Gown got up to win by a nose. Dave's third horse lined up in the last of the day and also crossed the winning post first. One distraught owner, two happy owners and one trainer in desperate need of a stiff gin!

Dave initially discouraged Paul from getting into training, wanting him instead to go to university and study accountancy. Paul had other ideas. He joined his father in 1981 and over the next 17 years, they achieved what most training partnerships can only dream of. They won every major race on the New Zealand racing calendar, multiple Group 1 races in Australia, including the Cox Plate and the Japan Cup, which at the time was the world’s richest race.

In 2004, Paul became the first New Zealand trainer to land a contract with the Hong Kong Jockey Club. Paul had enjoyed somewhat of a leg-up in his training career, however this would force him to start from the bottom in the toughest racing scene in the world. Paul’s determination and horsemanship skills shone through and over the past 17 years, Paul has excelled in Hong Hong and abroad.

The departure of Paul raised one very important question - who would take over the champion New Zealand stable? Following his retirement from the saddle in 2003, Lance found himself longing for more excitement and felt he was too young to retire. The adrenaline rush he got from winning races was addictive and something he was not ready to let go of just yet. Despite previously stating he would never train, Lance took over the reins at Wexford. Lance admits that the thrill he gets from training a winner is far greater than the thrill he got when in the saddle.

Andrew Scott joined Lance in partnership in 2006, following working under Mike Moroney at Ballymore Stables for over 15 years. Andrew continued as the sole trainer at Wexford when Lance stepped back in 2009, The success continued, with the headline acts My Keepsake winning the Gr.1 Queensland Oaks and Miss Raggedy Ann winning the Gr.1 Railway Stakes. He has since taken his tally in 20 years of training past 600 wins and is once again in partnership with Lance O’Sullivan.

Today, Lance and Andrew are at the helm of the Wexford ship. Paul is still training in Hong Kong and speaks to Lance (who he calls 'sporty') everyday without fail.

In 2003, Lance was made an Officer of the New Zealand Order of Merit, for his services to thoroughbred racing. In 2006, he was part of the inaugural class inducted into the New Zealand Racing Hall of Fame and in 2016 was inducted into the New Zealand Sports Hall of Fame. 

Dave was inducted in the New Zealand Racing Hall of fame in 2006 and the O’Sullivan Family gained New Zealand Racing’s highest honor when awarded the Racing Excellence Award. Lance also achieved this award on his own right some few years later.