I am highly impressed with your logic! I personally pictured Ten and Rose, but then I always picture Ten and Rose, because they are definitely the best. XD

I've seen this theory on TV Tropes as well and think it makes perfect sense. After all, there MUST be a reason aliens never land in, say, Tibet.

Invaders who do their research? Impressive.

A writer who comes up with an in-story reason for targetting London? Brilliant!

"Cosmetic tumor" is a terrific description.