I have some of Gerry's electric blue partridge and they are great in patterns like these when you want a bit more mobility to the front hackle than Jay would give,
Another alternative that I find even better is Dyed blue pheasant rump, as there usually sold on a patch and you can sort and find feathers easier, there is also a natural iradescence, I'm guessing Gerry will have these also.
I quickly tied this up to show the difference,
Claret Bumble Variant - as previous but with Blue Pheasant Rump
Cheers
Ben