I remember an interview with Gaiman where he said that it would be a shame to never get to write for Capaldi since he could hardly pass-up a Scottish Doctor. Now that Capaldi is gone, I agree. It definitely was.
Yeah. I've been reading a bunch of back issues of Doctor Who Magazine recently and they use that expression a lot! I've been very confused. You Brits can be so British sometimes!
Also, I seem to recall "The Doctor's Wife" also had to be scaled down considerably for budget reasons. I'm blanking on the particulars, but I believe that lead to them using the makeshift TARDIS console and bringing the Tennant console out of moth balls. I think Gaiman wanted to feature a lot more consoles. If they were able to make it work for "The Doctor's Wife," why not "Nightmare in Silver"?
IIRC, the original plan was to do "The Doctor's Wife" at the end of Season 5 but they ran out of money and replaced it with the much cheaper "The Lodger." "The Doctor's Wife" was then pushed back to Season 6.
BTW, I recall that something similar happened in Season 2, where there was an episode written by Stephen Fry that ended up being too expensive, so they replaced it with "Fear Her" and RTD announced that Fry's episode would be in Season 3. Whatever happened to that?
Nightmare in Silver was part of the seventh season, a year Moffat has admitted to feeling overworked and burnt out during (mostly due to things related to the fiftieth anniversary).
The more I look back on it, the worse Season 7 looks. The first half with Amy & Rory feels like a pointless addition to where we already left their story in Season 6. The 2nd half suffers from Smith & Clara having almost no chemistry together. Season 7 is the only season of the new series that fails to have even one episode that I would count as truly great. ("The Day of the Doctor" is a special. I don't count it as part of the actual season.)
Good question: What is Matt Smith's best-ever performance as the Doctor?
Depends on how you phrase the question. Matt Smith's best ever
Doctor Who performance was his double role as both the Doctor & Mr. Clever in "Nightmare in Silver." However, his best ever performance
as the Doctor is a trickier question. He's got some great bits in "The Eleventh Hour," "Amy's Choice," & "The Lodger." He shows some great range in "The Impossible Astronaut," going from his most goofy ("Oi, I'm up here being clever and no one is up here looking impressed! What's the point of any of you?!") to his most serious ("Don't play games with me. Don't ever, for a moment, think you're capable of that.") But, after careful consideration, I need to give the award to "The Pandorica Opens"/"The Big Bang." From his monologue to the monsters to his attempts to distract the Cyberman ("Look at me! I'm a target!") to his heartfelt goodbye to Amelia to his triumphant return just in time to invent the Drunk Giraffe dance, it's all the Matt Smith you could ever ask for distilled into a single 2-parter!