Henry de Bromhead's charge went to post a 10/11 shot on his return to action in the Listed contest over two-miles-seven.
It proved a real test of stamina on the heavy ground but the Saddex gelding jumped well throughout.
Blackmore let her mount hit the front at the last with over a circuit to go and asked him for an effort swinging for home.
The Big Dog got very tired in the straight, finishing 58 lengths back in third.
Eklat De Rire, a Grade 3 winner as a novice, was last seen in the action at Cheltenham when unseating in the Brown Advisory Novice Chase won by Monkfish.
It was Blackmore's first winner since returning from injury at the weekend and she said:-
"It's great to be back and it's lovely to ride a winner on that horse.
“He is a really, really nice horse and I think he is going to have a big future. I was disappointed with myself after what happened with him in Cheltenham, so it was nice to get him back on track today."
De Bromhead added:' "I'm happy with that, he is a grand horse. We were a bit unlucky at Cheltenham, how it would have fared, who knows.
“I'm delighted for Peter Davies, he is a great supporter of ours and it's nice to win this race. Today was to get him started and try to get him some confidence back.
“We have entered him in the race at Newbury, the Ladbroke Trophy, we just entered him in that this morning. He could possibly go for that, I'm not sure.
“We will take it one day at a time with him. Rachael said he was pretty straight today and we had him ready for it."