Thats the Garry Dog.

This pattern is reputed to have been born in a tackle shop where a visiting
minister was asked for some hair from his accompanying Golden Retriever’s tail.
This was used to form part of the wing of a fly being tied in the premises.
Nowadays a substitute of yellow bucktail or similar hair is used for this part
of the wing. The name of the dog was supposedly Garry hence the name Garry dog.
 Others say it was the ministers name hence Garry’s dog I sometimes wonder
if it has connections with the River Garry in the Scottish Highlands. Regardless
of its origin the Garry Dog has taken many Salmon and Trout and it is a very
successful fly.

I suspect that the Mickey Finn takes after this fly.
Cheers,
C.