The toilet roll dilemma - an online experiment

Every now and then I feel the urge to do an online experiment - today we are dealing with one of the biggest social issues to face humanity. Which way do you put the toilet roll on the holder?

I am personally convinced there is only one way for a sane person to do this, but not everyone agrees.

So what do you think? Which way up should we put the toilet roll? I'd be grateful for as many replies (here or on Facebook/Twitter @brianclegg) as possible.

Please don't just vote, though - I would like a logical explanation, with workings where relevant.

Thank you in anticipation. Littlendians and Bigendians have nothing on this one.