Good argument, and there is only one correct answer. The loans started a while before the grants ended, but if it is the start of new system, then it is the Ucas application year that ended in 2007.
If you applied in 2007, then you were eligable for a reduced loan, but could also apply for a (measly) grant.
If you applied in 1998, then you could get a much higher loan under the new system, and had to pay fees! but no grants were available.
I say it is when you apply, because I applied and got a place on the 1997 intake, but deferred my place for 12 months, so whilst the rest of my start year were under the new system, I was still under the old one.
So, the answer could be 1997 or it could be 1998, or you could live in Scotland and still get one, and not pay fees......