Well,

He refused to destroy the Dalek's in "Genesis of the Daleks" so he would be responsible in that case.

Of course, Being the Doctor Gallifrey is only destroyed some of the time

I hope you're right about an over riding story arc but I'm not convinced yet!

Pete

God is our guide! from field, from wave, From plough, from anvil, and from loom; We come, our country's rights to save, And speak a tyrant faction's doom: We raise the watch-word liberty; We will, we will,we will be free!