The hook is a Hanak H 300 BL (Size 12).
The thread is UTC 70 Fl White (The fancy bit?).
Under body is sticky lead sheet cut to about 1mm, three layers creating a fat bit in the middle tapering to nothing at each end.
Rib is thin copper wire.
The dubbing i haven't the foggiest idea.
Shell back is Siman something or other. Its shiny,stretchy and very very thin.
Nothing fancy STD, I thought all my flies are simple with a few ingredients

This ain't mine anyway its a Dave Downie pattern
And Yes Dave the shell back is tied in first, albeit not over the lead, behind the lead thus maintaining the taper.