Troy, a big, powerfully built bay horse with three white socks, was bred in County Meath, Ireland, by the Ballymacoll Stud, the breeding operation of his owners, industrialist Sir Michael Sobell and his son-in-law Lord Weinstock.

Troy made his racecourse debut in summer of 1978, wearing the light blue silks of his owners, when he finished second in a six furlong maiden race.

Starting at odds of 2/1[5] he was restrained by Carson at the rear of the six-runner field before taking the lead in the final furlong and winning by two and a half lengths from Ela-Mana-Mou.

[6] Troy was again moved up in class and distance for his final start of the year in the Group Two Royal Lodge Stakes, over one mile at Ascot Racecourse in September.

He chased the leader Lyphard's Wish before taking the lead a furlong from the finish but was overtaken in the closing stages and was beaten three quarters of a length by Ela-Mana-Mou.

Milford, also trained by Hern, was owned by the Queen and was popular with the public, but had been passed over by stable jockey Willie Carson in favour of Troy.

"[12] At the end of the June, Troy contested the Irish Derby at the Curragh in which he was reopposed by Dickens Hill, with the other runners including the French challengers Scorpio and the undefeated Fabulous Dancer.

He started the 4/5 favourite in a field of twenty-two runners which included Top Ville, Le Marmot, Three Troikas, Fabulous Dancer, Ile de Bourbon, Trillion, Crimson Beau, Two of Diamonds and Northern Baby.

Troy was given a rating of 122 by the independent Timeform organisation, twelve pounds behind Tromos and was described in their annual Racehorses of 1978 as "just the type to develop into a high-class three-year-old".

[6] Troy was given an end of season rating of 137 by Timeform in 1979, the fourth highest awarded to a Derby winner up to that time,[17] and was named their Horse of the Year.

[18] Troy's third-place prize money from the Arc took his total earnings to £450,428, a record for a horse trained in Britain or Ireland, which stood for three years until it was surpassed by Glint of Gold.

[17] Troy was syndicated by the Queen's manager of racing, Lord Porchester, for a then-record price of £7.2 million[19] and retired to stallion duty at the Highclere Stud, Burghclere Newbury, Berkshire.in 1980.