"It's already been talked about, them leaving me on a couple of their horses in the Finals Series races and I haven't had a good day at Flemington before, so I'm glad to get a couple of winners on the board."
Radley was pleased Seafall had a long straight on Saturday with the mare score a last-stride win in a three-way battle with Al Duca and Highlights to make it four wins from her past five starts.
"I always thought I was going to reel them in, but any other track than today I probably wouldn't have got there," he said.
Radley's two winners were not exactly roughies – Seafall started $5.50 and Stylish $7 – but they weren't as popular with punters as Johnstone's.
After winning the second race aboard $3.40 favourite Decalogue he was successful aboard the day's shortest-priced favourite, Ten Commandments ($2.10), in Race 5.
"Obviously none of this would have been possible without the support I'm getting and Ciaron Maher and his team and I can't thank them enough," Johnstone said.
"He's given me really good support and put a lot of trust in me."
Apprentices won more than half of the Flemington card, which started with Ryan Houston winning aboard Fontein Jewel for Ben Brisbourne and ended with Luke Cartwright scoring on Obvious for Greg Eurell.