He was bought for 520,000 guineas by the bloodstock agent Dermot "Demi" O'Byrne, acting on behalf of John Magnier's Coolmore organisation.

Ridden by Seamie Heffernan, he started at odds of 100/30 and finished fourth of the five runners, fifteen lengths behind the winner, Sugar Boy.

After a break of two months, Leading Light reappeared in a nine-furlong maiden race on heavy ground at Tipperary Racecourse where he was ridden by Kevin Manning.

Ridden for the first time by Joseph O'Brien, he led from the start and drew clear in the last quarter mile to win by seven lengths from the favourite Dibayani.

"[9] On 14 September, Leading Light was one of eleven three-year-olds to contest the 237th running of the St Leger over 14+1⁄2 furlongs at Doncaster Racecourse.

He was made the 7/2 favourite ahead of a field which included the filly Talent, winner of The Oaks and the colts Galileo Rock and Libertarian who had finished second and third in The Derby.

On his four-year-old debut, Leading Light started the even-money favourite for the Group Three Vintage Crop Stakes over fourteen furlongs at the Curragh.

He took the lead approaching the final furlong and drew clear to win by three lengths from the 2012 Irish St. Leger winner Royal Diamond.

O'Brien tracked the leaders as the pace was set by the Irish mare Missunited before moving up approaching the final turn into the straight.

[13] Leading Light was brought back in distance for the Irish St. Leger Trial over one and three quarter miles at the Curragh on 24 August.

Held up by O'Brien in the early stages, he made progress in the straight but never looked likely to reach the lead and finished second, 6+1⁄2 lengths behind Brown Panther and a head in front of Encke.