Gai Waterhouse's childhood was dominated by the world of horse racing (as her father was the legendary Randwick trainer TJ Smith) but was lured into the world of modeling and acting. She successfully explored these avenues, appearing in the Australian drama "The Young Doctors", and then moved to England and featured in "Doctor Who: The Invasion of Time".
Upon her return to Australia, she succumbed to horse racing, and studied under her father for 15 years as an apprentice, before obtaining her own license in 1992, and, in due course taking the title of Randwick's leading trainer. In the season of 1994-1995, her father became ill, and conceded the Tulloch Lodge stable to her.
Three months later she prepared her first winner, and in October her first Group I when Te Akau Nick took out the Metropolitan Handicap. Her first classic winner came with Nothin' Leica Dane in the 1995 Victoria Derby. In 1996-97 she had 10 Group 1 victories, won the Sydney trainers' premiership, and became only the third trainer in history to record more than 100 winners in a Sydney season. She won further trainers' premierships in 2000-2001 with 153 winners, 2001-2002 with 137 winners, 2002-2003 with 156 winners, equalling the record set by her father, T.J. Smith, and 2004-2005 with 118 winners.
Included in her more than 70 Group 1 wins are six Metropolitan Handicaps, six Doncaster Handicaps, four Epsom Handicaps, the training of all three placegetters in the 2001 Golden Slipper Stakes, and a second Golden Slipper win in 2004.
Gai Waterhouse has been honoured with the VRC and Thoroughbred Racehorse Owners Association Archer Award for outstanding achievement and contribution to the racing industry; and in 2000 was voted the Telstra NSW Businesswoman of the Year.
Gai's milestones include:
- Gai Waterhouse was inducted into the Australian Racing Hall of Fame on Monday 26th November 2007.
- Recorded 11 group 1 wins in 2004/2005 season setting her all time record
- Equalled her all time best record with 11 Group 1 Wins in the 2006/2007 season
- Licensed AJC trainer January 3, 1992
- Gifted Poet - first winner March 15, 1992 Hawkesbury Superfecta Hcp
- First Group winner - Moods (1992 Gosford Cup Group Three)
- First Group One winner - Te Akau Nick (October 5, 1992 AJC Metropolitan)
- First classic winner - Nothin' Leica Dane (1995 VRC Victoria Derby)
- Third trainer in history to prepare 100-plus Sydney winners (season 1996-97 104.5 wins)
- 100th black type win - May 1998 with Zabeel filly Zacheline
- Won Sydney trainer's premiership 1996-97 with 104.5 wins
- Recorded 10 Group One wins in 1996-97 - only the sixth trainer to do so in one season.
- Winning the Gr 1 AJC Doncaster Handicap in 4 successive years - 6 times in 12 years.
- Being the only trainer to quinella the Doncaster and Sydney Cup (both Gr 1) in the same season .
- Winner of the 2001 Golden Slipper trifecta with Ha Ha, Excellerator and Red Hannigan - a feat never achieved in this race.
- Equalling her father's record of training 156 metropolitan winners in a season, in 2002-03.
- Training 2004 Champion 2YO of the Year Dance Hero to become the horse to win the Magic Millions and Golden Slipper, as well as the Sydney 2YO Triple Crown.
- Honoured with the VRC and Thoroughbred Racehorse Owners Association Archer Award for outstanding achievement and contribution to the racing industry
- Presented the Sarah Kennedy Award for Contribution to Racing
- Winner of the Westpac Business Owner Award and named the states top businesswoman as the Telstra NSW Businesswoman of the Year 2000.