Charlotte Dujardin's former ride, now piloted by 17-year-old Annabella Pidgley, won their Intermediate II class with 77.304%.
The London crowd was delighted as the pair sparkled in the 4th leg of the FEI Dressage World Cup 2021/2022 Western European League.
Charlotte Dujardin, reunited with her Tokyo Olympic mount Gio, set a new personal best score of 82.553%, while Fuchs takes the Santa Stakes.
The British team and individual bronze medalist at Tokyo has sold 'Pumpkin' to up-and-coming junior rider Annabella Pidgley.
The German captured her third gold medal of the week on home soil riding Dalera, over Cathrine Dufour (DEN) and Charlotte Dujardin (GBR).
There were tears and cheers as the German ruled the ring with high scores, an Olympic GPS record and an unbeatable Freestyle.
Two great rides on Sunday from Dorothee Schneider with Showtime and Isabell Werth with Bella Rose secured the pole position.
Charlotte Dujardin has chosen a horse with limited ring experience for her dressage title defence in Tokyo.