De Mestre won the first two Melbourne Cups with Archer in 1861 and 1862, and later trained a further three winners: Tim Whiffler (1867); Chester (1877); and Calamia (1878).

De Mestre also trained many other feature race winners including two AJC and two VRC Derbies and an Epsom Handicap.

In the racing industry one could best describe Etienne de Mestre as the "Bart Cummings" (the greatest of all Australian Racehorse trainers) of the 19th century.

De Mestre's association with George Taylor Rowe (1822–1859) of Liverpool, England, the owner of the celebrated Veno, and the father of the little girl who was to grow up and one day to be his wife; and with his good school-friend Thomas John "Tom" Roberts (1831–1899) of Jembaicumbene near Braidwood, one of the owners of many champion horses including Mariner, Sailor, Archer, and Tim Whiffler, was at the forefront of a wonderful career of thirty years.

He occupied a leading place among the racing celebrities of Australia and was the first national sportsman to represent the Shoalhaven district where he lived.

As a school boy Etienne loved thoroughbred horse racing, and developed into an excellent horseman, amateur jockey, and trainer.

De Mestre spent his school holidays racing and working with the thoroughbred horses on his school-friend Thomas John "Tom" Roberts' "Exeter Farm" at Jembaicumbene.

It has been said that in 1847, at the age of 15, and just three years after his father's death, he won the main event at Bathurst on his favourite Roberts' horse Sweetheart.

One of Ellen's grandchildren, Guboo Ted Thomas[3] (1909–2002), who was born under a gumtree at Jembaicumbene, became a prominent Aboriginal leader, and she was the last initiated tribal elder on the South Coast of New South Wales; and one of her great grandchildren, Lloyd Nolan Hornsby[4] (1947–) was born in Brisbane to "Ellen" de Mestre's grand daughter Gladys.

There they established a horse stud, stable and racecourse where unofficial races were held and which was said to be the finest training track in the colony.

In 1857 Etienne de Mestre rode George Taylor Rowe's horse Plant to victory in the Liverpool Club's Members Plate.

Etienne became recognised as a master trainer, coming to prominence after leasing, training, and successfully racing Rowland Hassall & Tom Roberts' "Exeter Farm" bred colts Mariner and Sailor from 1857 to 1859.

When Archer was retired from racing he was not retained by de Mestre for breeding purposes but was returned to his legal owners at "Exeter Farm".

He frequently gambled on the wrong runner from his stable, and many times lost to the bookmakers all his considerable stake winnings from a carnival.

Although most successful as owner and trainer, De Mestre had been persuaded to invest heavily in Queensland property, and it was here that he ran into trouble.