Lokanaiya wrote...
Interesting. I had never seen that picture from Leviathan.
As for what the Reapers are doing in London, I'd say that at least a part of it would be setting a trap for the Resistance and, later, for the returning fleets. After all, if there are a lot of resistance members, including the leader, in one area, it would be a lot easier to sneak an indoctrinated agent in (Say, Coates) and/or indoctrinate the people there without attracting as much attention because hey, more people, and it would be easier to ignore strange behaviors or blame them on stress. For the fleets returning, the Reapers would probably prefer the main battles be in one area they prepared than guerrilla attacks across the entire world.
Admittedly, I know that isn't really enough explanation and doesn't offer a reason why it's specifically London, but it's a start. Maybe it'll make someone else think of something. 
About Coats, aside from him being as likely to be not indoctrinated as the literal ending, I think he's positioned there due to then Reapers essentially not being able to indoctrinate Anderson. The basic result of all indoctrinated people's beliefs is that the Reapers continue to live, that they don't fight them.
Saren believed we couldn't beat them, so we might as well joing them. He was aware of what the Reapers were and was working directly for them.
The Illusive Man believes that it's possible to control the Reapers, and will fight a war with the galaxy and kill anyone getting in his way. Unlike Saren, however, he believes he's still opposing them; but the bottom line is he's killing all those who want to kill the Reapers.
Dr. Kenson believed that, because the Reapers had come through before, but there was still life in the galaxy, how could we assume that they were coming to kill us all? Instead of using the means of slowing or stopping the Reapers we have in front of us, we should do nothing.
Two points at once here, first: Saren is Synthesis (siding with the Reapers), TIM is Control (being tricked by the Reapers), and Kenson...
Is Refuse! Arrival is choosing between a lot of innocent people dying by your hand, or stopping (slowing) the Reapers.Collector base was Destroy vs Control; Arrival was Destroy vs Refuse, but without the choice. Why no choice? Because Shepard's someone who acts, and no matter how Paragon, will get the job done no matter the cost!
My second point is, Indoctrination, at it's most basic, it identical to Inception: planting the very basic seed of an idea in someone's head, so they think it was their own. It has to be a really simple premise. Saren: Reapers are unbeatable, TIM: Control is possible, Kenson: We shouldn't assume the Reapers mean doom.
Now, how would you convince Anderson the Reapers need to survive in some fashion? The specific idea is not important, so long as a result of it is the Reapers not dying. Or Hackett? Or
Javik?

These are people who I could never, ever see indoctrinated. We're told that no one ever resists (other than Shep at the end), but I find it very unlikely every living being ever would fall for this.