I thought they were called 'Bf' until the Old Man (factory owner) died and Willi Messerschmidt (who had married the boss's daughter) took over. Then they changed over to 'Me'.
The official Luftwaffe designation was always Bf (short for Bayerische Flugzeugwerke). But it was commonly known as Me 109 among Allied pilots and even many Germans too.
"Upon my word I've had as much excitement on a car as in the air, especially since the R.F.C. have had women drivers."
James McCudden, Five Years in the Royal Flying Corps
