If you grab yourself a copy of the 1980 AD&D Dungeon Masters Adventure Log supplement, you can check for yourself. There's a filled-out example sheet at the back that has the following:
- Fred 9802 (male dwarf fighter) played by Dave Cook
- Black Dougal (male human ranger) played by Kevin Hendryx
- Sister Rebecca (female human cleric) played by Rebecca Moldvay
- Morgan Ironwolf (female human fighter) played by Tom Moldvay
The only elf in that product is "Elron Hubbard" (male elf fighter/magic-user) played by Lawrence Schick, and presumably that was changed to "Silverleaf" because nobody wanted to get sued by Scientology? :-)
Now granted, there's no way of telling whether these were really really really player characters short of asking (and I might be able to ask Dave when I see him next) but I find that to be a pretty reasonable assumption.
Also funny: Black Dougal is listed as "slain by a fire giant" in the Adventure Log so that poor guy always seems to end up dead. Sadly Sister Rebecca is also listed as "falls in valiant combat with a black dragon" so I am kind of glad that she survives in B/X.