To Canada and the always intriguing world of exiles, patriots and traitors. An excellent move sir. I'm thoroughly looking forward to the frozen and spy filled adventures Ian and Felix are bound to have.
I do wonder why Felix is still untrusted though, I can see the logic (he is an exile after all), but surely the time not to trust him was prior to Tube Alloys and meeting Einstein! If you trust him enough to do that you really should trust him for everything else. I can only guess their worried about him working against the US, even though it's evil commie US it still 'home'.
Icy and spy-filled, indeed. About the trust thing: You pretty much hit the nail, but M isn't the one behind it, more certain figures within MI6 feel that Felix might have problems with that. Ian on the other hand trusts Felix with his life, and rightly so I must add. M probably only asked because he was ordered to do so, but didn't tell because he was not exactly at 100% capacity. More on that later.