Re: Great Intelligence (Spoilers)
Konata pretty much says it all: everybody who's ever worked on Doctor Who has taken the sensible attitude that if continuity gets in the way of a good story, you ignore it (the fans will find a way to make it work: we already have several suggested ways to get round this problem). That's acceptable unless you miss an easy tweak which would have avoided the problem, or make the continuity central to the plot and then get it wrong.
"Some days are better than others. They say that where I come from."
"Loudly, I imagine, on the day you left."
(Blake's 7 - Rumours of Death)