To-Agori-Mou was a "big, rangy, attractive"[2] dark brown horse with no white markings[3] bred by the Rathduff Stud in County Tipperary, Ireland.
[4] As a yearling, the colt was sent to the sales and was bought for 20,000 guineas by the trainer Guy Harwood,[2] making him by far the most expensive of his sire's offspring sold in 1979.
[5] Starting the 8/11 favourite[7] he accelerated clear of the field in the final quarter mile and won by two lengths from Bold Raider, despite being eased down by Starkey in the closing stages.
He started odds-on favourite, but appeared short of peak fitness and was beaten three quarters of a length by the 28/1 outsider Kind of Hush.
Starkey held up To-Agori-Mou for a late run as usual and moved up to challenge Kings Lake, ridden by Pat Eddery in the last quarter mile.
Kings Lake's connections refused to accept the verdict and took their appeal to the stewards of the Turf Club (the regulatory body for horseracing in Ireland), who, after a six-hour hearing, reinstated the original result.
Kings Lake emerged as the challenger, but To-Agori-Mou prevailed in a "thrilling battle" to win by a neck, with the first two pulling six lengths clear of the other runners.
[10] To-Agori-Mou and Kings Lake met for the third time in the Sussex Stakes at Goodwood Racecourse on 29 July in which they were opposed by older horses.
[8] The fourth and final match between To-Agori-Mou and Kings Lake came in the Prix Jacques le Marois at Deauville Racecourse on 16 August.
To-Agori-Mou evened the score, beating his rival by a nose, but neither colt was any match for the French-trained four-year-old Northjet, who won easily by five lengths.
Later that month, To-Agori-Mou was matched against Moorestyle, the top-rated European racehorse of 1980, at two pounds worse than weight-for-age in the Waterford Crystal Mile at Goodwood.
[8] To-Agori-Mou was one of fourteen horses selected to contest the inaugural running of the Arlington Million in Chicago, but the invitation was not taken up, leaving the filly Madam Gay to represent Britain.
Ridden by Lester Piggott (Starkey was serving a suspension for careless riding),[12] he was held up at the back of the field before moving up to take the lead inside the final furlong.
He started 5/1 favourite, but after travelling well for most of the race he was unable to make any progress in the closing stages and finished fifth of the sixteen runners behind the French-trained colt Vayrann.