Is there any record of how many Northeast residents there were on October 1, 2007?
If you can find who was the Registrar General at that time and then find that person's census thread, it should be in there.
We didn't have Registrar General back then, and I don't think the SoFA kept record like the RG currently does. So, probably not.
I looked back through the history of the Wiki and found the unofficial list for 2007. The SoFA was Gabu, so asking him if he kept records isn't possible. Nor does his SoFA thread say much about the voter roll. The Wiki is the best evidence we're going to get, I think.