[7] Petrarch was a difficult horse to bring to peak condition, as he suffered throughout his racing career from intermittent kidney trouble.

Ridden by the little-known lightweight jockey Harry Luke,[16] Petrarch moved alongside the early leader Camembert three furlongs from the finish and then accelerated clear of the field.

[6] At least one commentator stated that Petrarch's poor performance in the earlier trial had been a deliberate ploy by Dupplin and his confederates to obtain better odds against the colt.

[19] It was later suggested that Petrarch's connections had never intended to win the race,[20] and that his poor performance had been deliberately engineered as part of a betting strategy.

In June Petrarch was sent to Royal Ascot where he won the thirteen furlong Prince of Wales's Stakes from Julius Caesar.

[21] One of the leading gamblers of the day, Lord Dudley, created a controversy when he refused to pay the £9,000 he had lost by wagering on Petrarch in his Ascot defeats, claiming that the horse had not been allowed to run on its merits.

[3] At Doncaster in September, the Derby winner Kisber started 7/4 favourite for the St Leger, with Petrarch, ridden my Jem Goater on 9/1.

Approaching the turn into the straight, Petrarch moved up to join the favourite, with the 100/1 outsider Wild Tommy also making good progress.

[22] As at Epsom and Ascot, there were rumours that the race had not been entirely fair: it was reported that Petrarch had been heavily backed to win by Kisber's owners, the Baltazzi brothers, who therefore stood to profit from the poor running of their own horse.

Ridden by the champion jockey Fred Archer, he started at odds of 9/1 and finished eleventh of the thirty-three runners behind the filly Footstep.

Ridden by Tom Cannon, his trainer's older brother, Petrarch traveled well until the turn into the straight when he seemed inclined to stop running.

[30] A match race between Petrarch and the Oaks winner Placida was scheduled to take place over six furlongs at Newmarket in autumn,[31] but never materialised.

[32] On his first run as a five-year-old, Petrarch started 11/2 favourite the City and Suburban Handicap at Epsom Downs Racecourse, but finished unplaced behind the future Derby winner Sefton.