It would have been easier to shoot him in the head with a silenced .22 and then stolen his wallet. A lot less suspicion would have fallen on the KGB that way. This was done to kill him publically, horribly and painfully as a warning to others.
That the KGB feels free to conduct a public killing in London shows the contempt the rest of the world (justifiably) holds the west in. That Blair is most concerned about "managing" the relationship with Russia shows the depths to which we have sunk. He should expel all their diplomats today.
We would do no better. Had this happened in the US, our State Dept would be busy working to smooth things out and cover up Moscow's involvement.
That's the "problem," I think. Who has suffered very long from a shot to the head?