Sonic screwdriver to the heart: The best temp in Chiswick

And after the temp from West London has only gone and saved the whole bloody universe, and upgraded to a whole new human/Time Lord creation, and helped all the Doctor's companions fly the TARDIS properly, the inescapable truth is that it just can't last.

Donna is resigned to her fate, but still fights it, and then the Doctor has to live with the aftermath. She is returned to her family, and he gets to speak to her one last time, but she has no idea who he is, even as he promises her mother and grandfather that her name will live on in the stars forever.

And just when it can't get any more heartbreaking, there's the last message from silly old Wilfred, who will one day be responsible for the Doctor's death. It's only Bernard bloody Cribbins in the rain, telling the Doctor he'll always think of him, even when he's alone out there in the universe.