He proved to be the first top-class horse owned by the County Waterford born Mulcahy, whose racing colours of green, white and orange were derived from the Irish tricolour.
[7] Thatch began his career with three easy wins at the Curragh, starting with the Corrib Maiden Stakes over six furlongs in June.
Ridden by Lester Piggott, he was strongly fancied for the classic, with his main opposition expected to come from the French-trained colt Targowice.
[11] By the summer, the dry weather led to firm, fast ground in England and Thatch returned in June for the St James's Palace Stakes over one mile at Royal Ascot.
[11] At the end of the month Thatch returned to the mile for the Sussex Stakes at Goodwood Racecourse, which at that time was restricted to three' and four-year-olds.
[13] Later in the season, Thatch was withdrawn from engagements in both the Queen Elizabeth II Stakes and the Prix du Moulin, as his connections did not wish to run the colt on soft ground.
[8] Thatch had some success as a breeding stallion, siring good winners over a variety of distances including Thatching, Achieved, Final Straw (four Group race wins including the Champagne Stakes), Tommy Way (Derby Italiano, Gran Premio di Milano) and Shulich (Gran Premio di Milano).