England pulled off one of the most remarkable Test victories of all time at Headingley on Sunday as Stokes made an unbeaten 135 in a one-wicket win against Australia that kept the series alive.
He produced his most incredible shots alongside last man Leach, with their unbroken 76-run partnership denying Australia, who would have retained the urn had they found a way to get either player out.
Leach, who only made one not out from 17 balls as Stokes brilliantly farmed the strike, has now confirmed that England's superstitious hero has made Ashes centuries in successive Tests wearing a box he borrowed from the tailender.
"He uses my box now," Leach explained to BBC Somerset.
"In the Lord's game, he had to get ready quite quickly. There were a couple of wickets and he lost his box so he was panicking.
"He was like, 'Leachy, can I borrow your box?'
"He was not out at the end of the day and he was like, 'This is going to sound weird, but I need to keep using your box'.
"So obviously I was like, 'Yeah, that's fine'.
"After that innings he was like, 'Mate, I'm going to have to keep that box now, it's a bit of a superstitious thing', and if Ben Stokes is happy, then I'm happy.
"It obviously worked again in this case."
Stokes made 115 not out in the second Test at Lord's, which ended as a draw, and appeared to be caught right in the area Leach's box was protecting from a Josh Hazlewood delivery during that innings.