How many prefects per house?

[justcarol67]

No: HPFGUIDX 91471

Sue: 
> In my theory, James would never have been a prefect. Lupin would have 
> been the prefect for their year through yrs. 5,6, and 7. Then, due to 
> some extrordinary circumstance, James was made Head Boy in their 7th 
> year without the prefect background.
>,snip>

Carol:
I don't think that your theory is a theory. It appears to be canon.
Prefects are appointed in the fifthe year, one boy and one girl from
each house, and remain prefects for the sixth and seventh years. Of
sourse the only example we have of this is Percy, but there doesn't
seem to have been any question that he wouldn't get his badge back the
next year. Percy is both a prefect and Head Boy in his seventh year,
but the prefect duties are more or less absorbed into or subsumed
under those of Head Boy. 

Most Head Boys and Head Girls are apparently prefects first, as both
Bill, Percy, and Lily were, but there are exceptions: notably James.
We know for a fact that he was never a prefect. Sirius says so in OoP.
Remus was chosen as prefect in their fifth year and presumably
remained a prefect all three years. As for why James was made Head
Boy, I don't think there's anything mysterious or extraordinary about
it. He was the best student in the school (the highest marks) and
Dumbledore honored him for his academic achievements by making him
Head Boy. Lucky Gryffindor would have had three seventh-year prefects
that year: James, Remus, and Lily, who was both a prefect and Head Girl.

Carol, who hopes that people who think MWPP were in Slytherin will
still see the point of the argument and not get sidetracked by the
last sentence