Rickaby, acting on Popham's behalf, bought the mare Ellen Middleton for 50 guineas and arranged her mating with the stallion Ion, the Derby runner-up of 1838 and a male-line descendant of the Byerley Turk.

[4] The colt was named after a local legend about one of Popham's ancestors, who had murdered an illegitimate baby by throwing it on a fire[1] and whose ghost was alleged to haunt Littlecote.

[6] Wild Dayrell was very backward and immature in the early part of his two-year-old season, and showed very little ability in his training gallops at Goodwood.

On 27 September he ran in a three-horse Sweepstakes and won very easily, beating Para and Hazel by two lengths[8] and impressing observers to the extent that he became regarded as a contender for the following year's Derby.

[9] In the spring, his owners decided that Wild Dayrell needed more challenging tests in training and bought a succession of increasingly able thoroughbreds against which to gallop him.

The process culminated in a trial race ten days before the Derby in which Wild Dayrell, ridden by the professional jockey Robert Sherwood, conceded twenty-one pounds to three rivals including a top class colt named Jack Shepherd and won easily.

Wild Dayrell's position at the head of the Derby betting made him the target of unscrupulous gamblers and bookmakers who stood to lose money if he won at Epsom and Popham responded by sacking a member of staff who had been behaving suspiciously and putting the horse under twenty-four-hour guard.

He next appeared at York in August where he won the "Ebor St Leger" in impressive style from a highly valued colt named Oulston.

Wild Dayrell was a difficult horse to assess, as he was never extended in any of his victories and was injured in his only defeat: one writer, reporting on his death commented that, "there is no saying how good as a racehorse he really was".

[3] R. H. Copperthwaite, in his book "The Turf and the Racehorse", offered the opinion that Wild Dayrell won the Derby with at least twenty pounds in hand.