I was a big fan of Jack's and the sparrow was his first "famous" fly, at least that was his first that I ever hear of.
It's cheap and easy to tie. It has lots of action and is representative of sculpin, nymphs, hoppers... what ever. A typical Gartside fly.
Palmering marabou my not be an original thought, but he's very specific on how it should be done on his original flies.
I have a copy of one of Jack's self-published booklets on his soft hackle streamer, and he goes into great detail on how to do it correctly.
In case you've never tried the soft hackle streamer.....they look so simple in the vice, but they're amazingly realistic in the water !
You need to try one.