"But what we didn't know was just what Moffat was going to do with his sole star had nothing else worked out. Apparently, he began drafting a version of the special where Clara was the lead character - and although The Doctor would appear, it wouldn't be any incarnation fans had ever seen on screen, not even Matt Smith's then-current iteration:
"So I came up with an alternate version of the 50th. Which was, the Doctor having stepped into his own time stream at the end of [season 7 finale] "The Name of the Doctor", he's eliminated from all of space and time, and Clara is trying to remember him. And the Doctor turns up in various fictional forms, and she says, "That story's true, that wizard, that was the Doctor," so she keeps encountering this, and we have the Doctor played by a succession of very famous people. That was my plan. "Very famous people."
Luckily, Moffat was granted a moment of hope when Matt Smith and former star David Tennant both signed up. Christopher Eccleston, who famously departed the series after just one season under less-than-amicable terms, declined to appear, necessitating the creation of a new "old" incarnation of the Doctor, played by John Hurt. According to Moffat, the decision was made so late that the script for "The Name of the Doctor" ended with a statement from the writer saying, "I'll figure it out when we figure out what we're doing for the 50th," rather than the scene that eventually revealed John Hurt's War Doctor."
C'est con, j'aurais p'têt préféré. 