I've reproduced below an interesting article that I came across in the March 1967 issue of the glossy British monthly publication "COINS AND MEDALS" (published by Link House Publications). There are three interesting points in this 42-year-old article:
1) the author contends that the Devil's Face was not noticed until it became necessary to change the Governor's signature from Towers to Coyne (this occurred on Jan. 01, 1955). I was always under the impression that the Devil's Face was recognized and reported immediately after the first 1954 notes were released.
2) Asterisk notes were evidently popular as early as 1967, and probably much earlier.
3). Solid serial numbers were evidently popular too!
{http://img.villagephotos.com/p/2008-1/1293040/DevilFace-Recognition-Date.jpg}
Logged
" Buy the very best notes that you can afford and keep them for at least 10 years. " (Richard D. Lockwood, private communication, 1978).