Philson Run finished fourth in a race that saw a false start and only 13 finishers.
Jockey Robbie Power guided his ride into an ideal position, assumed the lead over the last fence and finally squeezed enough pace from the gelding over the finishing straight to edge out McKelvey.
Earlier Slim Pickings had made the running alongside Libertine, but both saw their hopes fade under pressure from late surges.
The pre-race favourites failed to make any impression on the deciding stages on a good day for the bookmakers.
Point Barrow crashed at the first before Monkerhostin followed him out of the race at the seventh, while Hedgehunter and Numbersixvalverde failed to pick their way through the pack after being hampered by a fall from Royal Auclair.
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