The speedster was the only horse to break 55 seconds in the 17-race series sponsored by betting firm Ladbrokes, running 54.77s on October 26.
For good measure, Written Choice also ran the second fastest time in another heat of the series, clocking 55.22s on October 5.
McGill had to wait five months to find out if Written Choice's time would hold up.
“It's been a long wait but once they had gone two furlongs then I knew it was all over,” McGill told broadcaster racing.com.
“The $55,000 is the equivalent of winning a Group One race for a trainer.
“It's a huge boost and a really good concept to bring nice horses and fast horses to the races and that's what people want to see.
“We won a couple of these race along the way to make it even sweeter.”