Here's Adrian's recipe and comments for his swap fly.
Hook: Gamikatsu SC15 size 2
Thread: Primrose yellow
Underbody: Lead wire 0.030"
Body: Yellow chenille
Hackle: Orange Cock Hackle
Designed to be a fast sinking grub pattern with high visibility to assist in detecting when the fish has inhaled the fly.
Any passing resemblance to a couple of sweet-corn kernels is entirely intentional.