It doesn’t seem to me that it really matters if senior News International employees and owners actually knew the details of phone hacking.
They may or may not have demanded that no details were given to them, which would allow them to say that they did not know what was going on.
The real point, in my view,  is that they are just as culpable if they knew and encouraged phone hacking as they would be if they allowed staff to keep them in the dark about phone hacking!
They must have read the stories in their own newspapers and, if they were doing their job properly, they must have wondered where these stories were coming from!
Surely they would at the very least want to know who the successful reporters who had obtained these news scoops were in order to congratulate them!
Perhaps they did not even bother to read their own newspapers!
In my view the fact that they appear to have kept a Chinese wall between themselves and their reporters seriously damages their claims to not know that something was wrong in the organisation!