The 31-year-old Irishman goes while still in one piece. "I have been thinking about it for some time, basically for health reasons," he said.
"Whenever I've had a fall lately I have been left feeling dazed, which I didn't in the old days. As much as I love riding, I have to put my health before my career."
Culloty's departure distances what has been one of the greatest tales in modern National Hunt racing. Best Mate himself was absented from racing earlier this year, in his case temporarily, when he broke a blood vessel on the gallops. Now his regular partner has gone permanently.
This was, indeed, the holiest of alliances. Other jockeys have ridden Best Mate, most notably the multiple champion Tony McCoy, but none has ever seemed as compatible as Culloty. He was clever and calculating. The horse seemed to be the same. In this case, the two similarities attracted.
"It's a very sad day," Henrietta Knight, Best Mate's trainer, said last night. "They were such a superb partnership. I'm sure we wouldn't have won the three Gold Cups without Jim. He just got on with that horse from day one."
The first day for Culloty was in Killarney on 18 December, 1973, and he rode his first winner in Britain at Exeter in January 1994 for trainer Jackie Retter, who provided the then amateur with most of his early rides.
Access to the big-time came when the Irishman switched to Knight's West Lockinge establishment. The amateurs' championship came in the 1995-96 season and the following term he turned professional.
The alliance with Knight was to last a decade. It was punctuated by several very good horses and one outstanding animal. Culloty won 12 races on Best Mate, including a hat-trick of Blue Ribands (2002-2004).
Culloty and his wife, Suzie, had their first child earlier this year. The family is based on a farm in Co Cork and the plan is to rear young horses. All the time there will be the old ones on which to reflect.
The jockey won the Grand National on Bindaree in 2002 and the following season he collected the Irish equivalent on Timbera. There were five Festival winners and, finally, a second place at Market Rasen at the weekend.
"Jim rode a superb race on Impek on Saturday in the Summer Plate," Knight said. "We just said that evening that when he rides like that there is nobody better.
"It's come as a shock. I'm sad about it, but I was watching on television when Jim took some very heavy falls in Ireland last week and he's doing the sensible thing.
"He was a great jockey for the big occasion, and was always cool under pressure. You would never see Jim panic. He had an excellent record in the major races, for us and other trainers.
"Jim became a good friend and we will miss him. Although we agreed this year that he wouldn't continue as stable jockey, there was no falling out. We simply wanted to give him more freedom. He was picking up good rides in Ireland so there seemed little point in him dashing back for one of ours.
"I don't think anyone has ridden Best Mate round Cheltenham bar Jim. If we can get the horse right it will be very interesting to see someone else on him round there because they couldn't possibly do anything better than Jim. It won't seem quite the same when we go to Cheltenham without him. It feels like the end of an era."
HYPERION'S SELECTIONS FOR TODAY'S OTHER MEETING
WORCESTER: 2.10 Openide 2.40 Houlihans Free 3.10 Peeyoutwo 3.40 Parisian Storm 4.10 Cannon Fire 4.40 Excellent Vibes 5.10 Creagh Bay
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