A classic from the Frank Sawyer stable, I wonder if there is any river fisher's fly box that isn't graced by this simple pattern. In the true style, I prefer to use copper wire as the 'thread', but I really like addition of a tungsten bead. This results is a fly that, even in micro sizes, sinks quickly through the water column.
Worth noting perhaps that the whole pattern is tied with just one bunch of Pheasant tail fibres - perhaps just three or four.
The hook is the trusty Partridge SLD #20