My opinion on who won the House Cup in OoP

[Robert A. Rosenberg]

No: HPFGUIDX 67720

One of the unanswered questions in OoP is "Who won the House Cup this year?".

I think the answer is Gryffindor with somewhere in the 500-600 point 
range. Admittedly, there were only 240 points shown as being there 
after Professor McGonagall added the 250 points and approved Snipe's 
10 penalty but you have to look at the reason why they were at 0 (or 
negative) Points - Umbridge. Once she was kicked out, DD would have 
removed her from the list of authorized Points issuers and 
retroactively voided her input. This would have restored all the 
points she removed from Gryffindor as well as those points she issued 
to Slytherin. Given that Gryffindor tended to have in the 250-350 
point range by this time (remember they won the Q Cup again), this 
would put them in the aforementioned 500-600 range. Note that the 
voiding of Umbridge input is nonpartisan (it restored point to the 
other 2 houses also).

If Gryffindor still needed help against a Slytherin lead (I do not 
think they would), a "Bad Sportsmanship"/"Interference" penalty 
against Slytherin house for the "Weasley is our King" Song (which is 
in effect spell casting to affect the results of the Games) during 
the Slytherin vs. Gryffindor match as well as double penalty points 
for its use during the second, third, and fourth(?) matches (since it 
is not just "Cheering for Slytherin" then but only interference with 
the match since Slytherin's only interest in the game is to prevent 
Gryffindor from winning not to win itself - ie: Gryffindor losing 
just prevents them from challenging Slytherin in the standings) would 
take care of any points that Slytherin had which prevented Gryffindor 
from winning the House Cup (I know that using this method is partisan 
but so is Snipe's Points Granting/Removal behavior AND I only mention 
using it IF it is needed not just to reward Gryffindor with points 
they do not need).