The 24-year-old freelance stepped in for the ride on the Brian Meehan-trained filly when intended rider Jimmy Fortune was forced on the sidelines after receiving a kick at Salisbury 24 hours earlier.
And Winston enjoyed a pay-day he will not forget when the daughter of Barathea knuckled down bravely in the final stages to edge out the previously unbeaten pair, Suez and Damson.
Philip Robinson took Suez straight into the lead from her rails draw and set a good gallop.
Two furlongs out Magical Romance, Damson and Slip Dance lay down strong challenges to Suez as these four pulled clear of the other three runners.
Damson, the 10-11 favourite, looked to be getting there under Kieren Fallon when producing a challenge to the leader at the distance.
But it was Magical Romance who ultimately proved the strongest inside the final strides as she powered her way between rivals to beat Suez (4-1) by a neck with Damson the same distance back in third.
In fact, less than a length and a half covered the first five home in the six-furlong contest.
The winner had enjoyed an unusual preparatory route for Group One success and was following up a success in a run-of-the-mill Leicester nursery under Winston only 10 days ago.
But Meehan insisted that he had always held the filly in regard, saying: “We ran her in the Princess Margaret before Leicester where we thought she would finish in the first four but she got jarred up and her last win just helped to get her confidence back.
“She’s a lovely filly and has always shown plenty at home. The rain probably helped her a little bit but she’s a real nice filly. The way she ran would suggest that getting a mile next season would be no problem for her.
“Robert did a great job, too and it was an advantage that he knew her so well.”
Meehan was reluctant to discuss future plans for the filly until he had spoken to the absent owner, but admitted she had “probably done enough for the season now”.
David Wachman, trainer of Damson, thought his filly might have been feeling the effects of a busy season. “There are no excuses,” he said. “She seemed to labour in the last furlong. She came to win her race and didn’t seem to quite get home but I still hope she will stay a mile next year.”
Meanwhile, Diktatorial emerged as a live candidate for the 2000 Guineas with a resolute victory in the Somerville Tattersall Stakes.
After Andrew Balding’s juvenile had battled back to beat Crimson Sun by a neck in the seven-furlong Group Three contest, Paddy Power went 40-1 about his chances in the Classic.
Steady rain changed the going to good, good to soft in places but Martin Dwyer had no hesitation in sending Diktatorial straight into the lead.
Crimson Sun threw down a challenge a furlong out and briefly headed Balding’s youngster but Diktatorial forced his head back in front in the shadow of the post.