Sun Princess's sire, English Prince, won the Irish Derby, but was not a great success as a stallion in Europe and was exported to Japan in 1980.

[5] Sun Princess made her first appearance as a three-year-old in the Sir Charles Clore Memorial Stakes, at Newbury in May, a trial race for the Epsom Oaks.

In the straight she increased her lead with every stride to record a "highly impressive victory"[7] by twelve lengths from Acclimatise, with Royal Heroine (Breeders' Cup Mile) and Cormorant Wood (Champion Stakes) among the beaten fillies.

The winning margin was the largest ever recorded in the Oaks and the biggest in any British Classic race since Never Say Die won the St Leger by twelve lengths in 1954.

She made steady progress in the straight, but failed to reach the lead and finished third to Time Charter and Diamond Shoal, beaten just under two lengths.

Following her win at York, Sun Princess again faced mixed-sex competition in the St Leger Stakes at Doncaster on 10 September for which started 11/8 favourite.

Her main rivals included the Epsom Derby runner-up Carlingford Castle[8] and the Grand Prix de Paris winner Yawa.

The Hern stable entered a pacemaker named Sailor's Dance who led at a moderate gallop before Sun Princess took the lead in the straight.

[13] Descendants of Sun Princess remain at Ballymacoll through her granddaughter Drama Class (by Caerleon out of Stage Struck by Sadler's Wells).

Drama Class has had two black type offspring in Scottish Stage (by Selkirk: 2nd Irish Oaks) and Eleanora Duse (by Azamour), who are both also broodmares at the stud.

In contrast to her attitude during her racing career, Sun Princess developed a quiet and docile temperament in retirement: the Ballymacoll stud manager describer her as "a most wonderful character and a very easy mare to deal with.