The class dedicated to riders aged 25 and under saw the Frenchman, take the honours after starting the cross-country in second place.
Astier’s 47.2 dressage was followed by 2.4 time penalties on the cross-country before they jumped a superb clear round on the final day.
Said Astier: “The good thing is I know there is more to come! He was great on the cross country! He’s the most genuine horse I’ve ever had and he has a huge stride so just cruised round. He did tire at the end but he’s so generous that he gave what he had and even what he didn’t!
“I really loved the cross country and know I have a special horse as he jumped so well around it – I feel he can go around anything now! It was a real test for him as he is bred to show jump but everything went to plan and I am so happy.”