On 11 April 2015, ridden as in all of his previous races by Leighton Aspell, he carried 11 stone 9 pound to victory in the Grand National at Aintree Racecourse.
In January 2017, he beat the previously undefeated Thistlecrack in winning his second Cotswold Chase but collapsed and died of an exercise-induced pulmonary hemorrhage[2] shortly after crossing the finish line.
Many Clouds was a "big, old-fashioned"[3] brown gelding bred in Ireland by Aidan Aherne at the Windward House Stud in County Cork.
On his final start of the season, he was matched against more experienced hurdlers in the Injured Jockeys Fund Handicap Hurdle at Aintree in April but was pulled up by Aspell two flights from home.
On his debut over the larger obstacles, he won over two and a half miles at Carlisle Racecourse in November, beating the highly regarded Holywell into third place.
At Ascot on 15 February he was stepped up in class for the Grade 2 Reynoldstown Novices' Chase and finished second, beaten two and a half lengths by O'Faolains Boy.
He took the lead three fences from the finish and won from the favourite Eduard (winner of the Future Champion Novices' Chase), with Holywell fifteen lengths back in third.
[9] Later that month, Many Clouds was assigned a weight of 11 stone 6 pounds for the 58th running of the Hennessy Gold Cup over three and a quarter miles at Newbury Racecourse.
Starting at odds of 8/1 in a nineteen-runner field, he took the lead at the last fence and stayed on strongly to win by three and a quarter lengths form Houblon des Obeaux.
He disputed the lead from the start and stayed on strongly over the last two fences to win from Smad Place, Dynaste, The Giant Bolster, and Black Thunder.
[20] His final prep race for the Grand National was intended to be a chase at Kelso Racecourse on 5 March but the meeting was abandoned and rearranged to take place eight days later.
[23] On 28 January 2017 Many Clouds attempted to repeat his 2015 success in the Cotswold Chase at Cheltenham and started at odds of 8/1 in a seven-runner field which included Thistlecrack (the 4/9 favourite), Smad Place, and Silviniaco Conti.
After jumping well throughout the race, Many Clouds took the lead four fences from the finish and fought off the sustained challenge of Thistlecrack to win by a head in a photo-finish.
[26][27] In May 2017 the senior handicappers of Britain and Ireland named Many Clouds the leading staying steeplechaser of the 2016–17 season, rating him two pounds higher than Cheltenham Gold Cup winner Sizing John.