What great questions, Simon. I do think the execution of Nicholas and his family was an act of "revolutionary justice" (or if you want to call it, simply revenge) at least at the level of the Ural Regional Soviet. At the level of Moscow, the decision to kill the family was more a matter of logistics, IMHO. Of course whether or not Nicholas was a viable political player (I think Lenin knew very well Nicholas was a political has-been, unless you could put him on trial as an evil tsar-devil, as Trotsky had envisioned), it would have been counter-productive to let him fall into counter-revolutionary hands. (Remember the crucial symbolic importance, too, of executing the former tsar rather than letting him escape.) Moreover, why let his attractive children, especially the tsarevich, fall into counter-revolutionary hands? Everything was still very touch-and-go for the Bolsheviks in 1918, very up in the air and chaotic. They didn't know if they could hold on to power for very much longer, so why take the risk that the Whites might find a rallying point in the figure of the young tsarevich or his sisters? It wasn't a very likely prospect but anything could happen, and they would have been fools not to have considered the prospect. That said, I don't think the decision to execute the IF cost Lenin any sleepless nights or even much mental exertion. I think it was just one more blip on his cerebral radar screen... Whether the URS acted on their own or with the advance approval of Lenin, the fact was that Lenin speedily approved the action within hours of the murders. Clearly, he had no regrets.