Petite Etoile was a filly

Filly

A filly is a young female horse too young to be called a mare. There are several specific definitions in use.*In most cases filly is a female horse under the age of four years old....

 of the highest quality, but her success would hardly have been anticipated by those who saw her in her first race as a two-year-old when she was beaten by eight lengths in a two-horse race. After that, though, she never looked back and Petite Etoile claimed the honours in the Free Handicap

European Free Handicap

The European Free Handicap is a Listed flat horse race in Great Britain which is open to three-year-old thoroughbreds. It is run on the Rowley Mile at Newmarket over a distance of 7 furlongs , and it is scheduled to take place each year in mid April.It is a handicap in which horses carry weights...

 on her first appearance at three, before taking the 1,000 Guineas. Not everyone was sure she would stay the one and a half miles of the Epsom Oaks

Epsom Oaks

The Oaks Stakes is a Group 1 flat horse race in Great Britain open to three-year-old thoroughbred fillies. It is run at Epsom Downs over a distance of 1 mile, 4 furlongs and 10 yards , and it is scheduled to take place each year in early June....

 but she did so without problem and went on to triumph in the Sussex Stakes

Sussex Stakes

The Sussex Stakes is a Group 1 flat horse race in Great Britain open to thoroughbreds aged three years or older. It is run at Goodwood over a distance of 1 mile , and it is scheduled to take place each year in late July or early August.-History:...

, Yorkshire Oaks

Yorkshire Oaks

The Yorkshire Oaks is a Group 1 flat horse race in Great Britain open to thoroughbred fillies and mares aged three years or older. It is run at York over a distance of 1 mile and 4 furlongs , and it is scheduled to take place each year in August....

 and Champion Stakes

Champion Stakes

The Champion Stakes is a Group 1 flat horse race in Great Britain which is open to thoroughbreds aged three years or older. It is run at Ascot over a distance of 1 mile and 2 furlongs , and it is scheduled to take place each year in October...

. In 1960, she easily beat the 1959 Epsom Derby

Epsom Derby

The Derby Stakes, popularly known as The Derby, internationally as the Epsom Derby, and under its present sponsor as the Investec Derby, is a Group 1 flat horse race in Great Britain open to three-year-old thoroughbred colts and fillies...

 winner, Parthia

Parthia (horse)

Parthia was a British Thoroughbred racehorse and sire. In a career that lasted from October 1958 to July 1960 he ran twelve times, winning six races, four of which are now Group races. His most notable success came in the 1959 Epsom Derby...

, before losing the King George VI and Queen Elizabeth Stakes to Agressor in what has long been regarded as a race in which other jockeys combined to make things difficult for Lester Piggott

Lester Piggott

Lester Keith Piggott is a retired English professional jockey, popularly known as "The Long Fellow". With 4,493 career wins, including nine Epsom Derby victories, he is one of the most well-known English flat racing jockeys of all time....

. As a five-year-old Petite Etoile claimed a second Coronation Cup

Coronation Cup

The Coronation Cup is a Group 1 flat horse race in Great Britain open to thoroughbreds aged four years or older. It is run at Epsom Downs over a distance of 1 mile, 4 furlongs and 10 yards , and it is scheduled to take place each year in June....

 and was also victorious in three other races. She retired as a winner of 14 races worth £72,626. However, in subsequent years, her career as a broodmare was nothing short of disastrous.