Simon posted a five-under par 66 to edge out a group of six players, including former Ryder Cup star, Philip Walton, by one shot in Co. Tipperary.
“I played nicely, well, a mixture of some good stuff and bit of luck,” said Simon who produced a bogey free round after starting his day on the fifth.
“To be honest I haven’t been playing very well at all. For 13/14 holes I played lovely, gave myself loads of chance. Fairways hit, holed a couple.
“I was four under and then I played the 18th. Missed a drive there, hit the trees and had a route out.
“At the first, I hit another tree, it bounced back and I had a route out and then the same happened again at the third. I hit it up to the side of the green with my second shot and it finished against a wall on a pathway. I duffed my chip but chipped in for a par.
“I haven’t really had a good season golf wise as much as I am still up there fighting.
“We are coming into a busy spell now, I’ll be playing a lot of golf over the next few weeks so hopefully this win could get me going.”
The team prize was won by David Higgins (Waterville) with amateur partners Tommy Flynn, Jody Boyle and Gemma Murphy.
Morrison BMW Cahir Park Golf Club Pro-Am
at Cahir Park Golf Club (Par 71)
1 S Thornton (Tulfarris Golf Resort) -5 66
T2 D Mooney (Damian Mooney Golf) -4 67
T2 P Walton -4 67
T2 D Higgins (Waterville Golf Links) -4 67
T2 M McGeady (Evolve Golf Coaching) -4 67
T2 B McElhinney (Evolve Golf Coaching) -4 67
T2 D Ryan (Cahir Park GC) -4 67