Only after a titanic struggle with Coltrane did Trueshan secure a hat-trick of victories in the QIPCO British Champions Long Distance Cup.
The 11/8 favourite pursued the leaders throughout the race, but after turning in to get a clear shot at them, she had to be switched.
He started squabbling with the eventual runner-up at the two-furlong pole, and the only space they ever had between them was the head, which was the designated winning distance.
Trawlerman, who was in third place, was three lengths behind.
Winning jockey Hollie Doyle said: “What a horse. I’m speechless to be honest. Alan King is the maker of this horse. From what he has done today on the back of his last two runs is phenomenal.
“It was really rough going into that first bend. I had Wordsworth on my outside. I was caught in a pocket and it was one of them where you either kick in or get flattened. I kicked in and some people suffered as a consequence.
“For someone like me, I’m quite emotionally invested in the sport and this means the world to me.”