Coupe, 46, triumphed on Sunday June 25, riding 14-year-old Irish Sport Horse Golvers Hill (Ricky) who is owned by Susan Simmons.
Only two horse and rider combinations managed to jump clear from 26 starters, leaving Samlesbury-based duo Coupe and Harriet Nuttall to jump-off for the honours at the 57th renowned Hickstead Derby at the Sussex showground.
Coupe finished with four faults in the second round to seal the win, just ahead of Nuttall who finished in a slightly slower time and on eight faults.
And Coupe, who has had previous minor placings in this class, and was equal second in 2015 dubbed the victory his biggest win 27 years after his first entry at the prestigious competition back in 1990.
He said: “It’s amazing. However you can imagine it feels, it probably feels about 100 times better!
“Ricky found me really – it’s amazing to finally do something like this. It’s tough on Harriet as she’s such a nice girl but I’m still pleased I won! You just keep going and eventually your luck will turn. Honestly I didn’t think it was my year.
“My horse - I’m forever indebted to him. I was teaching Sue on him, and as an eight-year-old he was doing Working Hunter, Foxhunters and Newcomers at HOYS. The next year Sue did Working Hunters and luckily for me she didn’t have such a great year, so she sent him to me and I quickly upgraded him to a Grade A.
“He likes the limelight. He just loves his job
“I can’t wait to go over there and it’ll say ‘Nigel Coupe’ on the wall.
“Nobody can ever take that away from you.”