Aurelius's dam was Niobe, an American mare bred by William Woodward Sr. who was bought and imported to Ireland on the advice of Cecil Boyd-Rochfort.
[5] At Royal Ascot in June, Aurelius started a 20/1 outsider for the King Edward VII Stakes over one and a half miles.
[2] On 9 September, Aurelius was one of thirteen three-year-olds to contest the 185th running of the St Leger Stakes over fourteen and a half furlongs at Doncaster Racecourse.
Later that month he produced what was arguably his best performance when he finished second by three quarters of a length to the French-trained Match in the King George VI and Queen Elizabeth Stakes at Ascot.
[8] In their book A Century of Champions, John Randall and Tony Morris rated Aurelius an "average" St Leger winner and the best British-trained racehorse of his generation.
[2] In the 1965/1966 National Hunt season he showed some promise as a hurdler, finishing second in a division of the Gloucestershire Hurdle at the Cheltenham Festival and then returned to the flat to run second to the dual Ascot Gold Cup winner Fighting Charlie in the Henry II Stakes at Sandown.
In March 1967, Aurelius produced his best performance over obstacles when he finished second to Saucy Kit in the Champion Hurdle although he was then disqualified for causing interference in the closing stages.