McGonagall

[Freeman, Louise Margaret]

No: HPFGUIDX 89989

//"How long have you been teaching at Hogwarts?" Professor Umbridge 
asked. 

"Thirty-nine years this December," said Professor McGonagall 
brusquely, snapping her bag shut.//

Hmmm...  wouldn't a teacher normally begin in September?  Sounds like 
McGonagall was a mid-year replacement for someone.  This suggests that 
something unfortunate happened to the previous Transfiguration teacher 
mid-year.  Or perhaps the headmaster; since Dumbledore was teaching 
Transfiguration 50 years ago, he could have been in that position then moved 
to the Headmaster post when it was vacated. McGonagall would have then been 
hired to replace him.

Louise