I believe both a three fingered and a two fingered draw were used. Doesn't Ascham talk of the use of three fingers? Also didn't the various French laws concerning the removal of captured English Archer's fingers variously talk of two or three? Could of course be wrong on both accounts but have dredged them up from the old memory.
Legend tells us of the two fingered draw and the two fingered salute to the French after victory to show that the shooting fingers are still intact.
Having thought about my first statement regarding Ascham I decided to dust off my copy of the book and see if my memory was correct so I edited this response and added the following:
Ascham, in Toxophilus book 11 page 101 in the 1990 Simon Archery edition, says:
"And when a man shooteth, the might of his shoot liest on the foremost finger, and on the ringman: for the middle finger which is longest, like a lubber, starteth back, and beareth no weight of the string in a manner at all"
Thus a three fingered draw in which the middle finger does very little work.
Craig