"Killing people is never easy, but killing old friends can even get a bit emotional," admits Steven Moffat in the latest issue of Radio Times.
Writing exclusively for the magazine, the Doctor Who supremo describes how he struggled to decide on the perfect final farewell for companions Amy Pond and Rory Williams, aka Karen Gillan and Arthur Darvill.
"How and why would they leave? And would they live or die?" asks Moffat. "I wrote and rewrote. I had a completely different ending and threw it away...."
"So many times over those mad few days, the fate of the Ponds changed. Alive, dead, alive, dead.... Nothing felt right. Nothing felt inevitable."
Get the latest issue of Radio Times, on sale now, to find out how, in the wee small hours, Moffat finally had his eureka moment - and why an "old, sentimental" and "dangerous" Doctor meant the Ponds had to die...