[11] Kilwarlin began his second campaign by being matched against older horses in the Great Jubilee Handicap over one mile at Kempton Park Racecourse on 7 May.

[12] At Royal Ascot in June he was matched against the 1886 English Triple Crown winner Ormonde in the Rous Memorial Stakes and finished second, beaten six lengths by his older rival.

[16] On 14 September, at Doncaster Racecourse Kilwarlin was moved up in distance to contest the 112th running of the St Leger over fourteen and half furlongs and despite what was described as "wretched" weather the race attracted its customary large crowd.

[17] Ridden by Jack Robinson he was made the 4/1 favourite ahead of Eiridspord while the best fancied of the other runners were Merry Hampton (winner of the Epsom Derby), Scottish King and Phil (runner-up in the 2000 Guineas).

[2] Kilwarlin was unruly in the paddock and Robinson opted to abandon the colt's participation in the parade in front of the stands as his behaviour deteriorated.

[17] When the flag fell to start the contest Kilwarlin "dug his toes in" and refused to race, and the other runners had covered at least 100 yards before Robinson persuaded him to take part.

[19] After moving into contention on the final turn, Kilwarlin took the lead a quarter mile from the finish but was immediately challenged by Merry Hampton and Timothy.

After what was described as a "ding dong" struggle and one of the best finishes even seen at Doncaster, Kilwarlin prevailed by half a length from the Derby winner, with Timothy a head away in third place.

[20] The result produced some controversy as Robinson's rival jockeys were criticised for allowing the favourite back into the race instead of setting a faster pace which would have eliminated Kilwarlin from contention.