His upset win in the classic, followed by a poor run over the same course and distance two days later, attracted a great deal of comment and suspicions of race-fixing, although none of the allegations was ever proved.

[6] A month later he ran at the St Leger meeting at Doncaster Racecourse where he carried 80 pounds in an all-aged handicap race and finished second to the four-year-old Dunsinane.

A few days before the race, James Croft had run Theodore in a training gallop against his three other St Leger contenders, Violet, Corinthian and a grey colt owned by the Duke of Leeds.

[17] His jockey, John Jackson, was so upset at being ordered to ride the colt that he allegedly burst into tears,[2] whilst Edward Petre was said to have sold off all the bets he had made on the horse for £200 to Mr Wyvill.

[18] Jackson sent Theodore into the lead from the start, and after holding off the challenges of Pilgarlick, The Whig and Richard Watt's Mandane filly, he pulled ahead in the straight and won easily[19] by a length from Violet (50/1) with the Duke of Leeds' colt (200/1) taking third place.

[24] The widely divergent form exhibited by Theodore and Swap at Doncaster led to a great deal of comment, and there were strong suspicions that one or other of the races had been a "cross".

[26] A later writer offered the view that Theodore was a good, fast horse, well-suited to the prevailing soft ground, and that his poor performance in the Gascoigne Stakes was due to his aggravating an existing injury when winning the St Leger.

[29] Two weeks later, and carrying a three-pound weight penalty for his win at Manchester, he started favourite for the Gold Tureen at Leeds Racecourse but was beaten by Mr Ferguson's Wanton.

[30] Theodore ran twice at York's August meeting, finishing second to Sandbeck in the Fitzwilliam Stakes and third to Carnival in a division of the Great Subscription Purse.

[31] On his final start of the season he ran at the St Leger meeting for the fourth consecutive year, finishing third of the eight runners behind Mercutio and Lottery in the Gold Cup.

[33] In September, Theodore became the property of a Mr Dobbie and was sent further north to compete at Inverness where he finished second to Lord Kennedy's Skiff when favourite for the Trial Stakes.