The idea is not a new one - Oswald Rayner's wikipedia entry, for example, mentions his involvement in the plot, or just google Rasputin and Rayner. It's going a bit further to look at MI6 as instigators or knowing collaborators, of course, but it would have been terribly remiss of Rayner, then in their employ, to go about assisting in murders of national figures without seeking approval.
Jemahl Evans has some interesting points in his Bullingdon Club piece at http://jemahlevans.wix.com/jemahlevans#!A-Brief-History-of-T... though that url does't play nicely with my mobile device.