In reply to Rick Sewards:
An update to this - it appears (though it's not confirmed yet) that they (I assume it's the same pair) have moved on to the far left hand end of North Wall, either at the same level as, or above the Great Ledge, and to the left of the finish of Left Hand Route. For the moment the restriction on the far right hand end of GO Wall described above remains in place, but in addition please avoid Left-Hand Route and the other routes that finish or start on the left hand end of the Great Ledge - including Gryke, Punch and Judy, Suspect Device, Exodus, Tarnhelm and Bacchanalian. There are no signs in place yet (I only became aware of this today, when I saw them - and a freshly decapitated pigeon on the Great Ledge!) but will be soon, and I hope to resolve asap exactly where they are nesting. If they are no longer on GO Wall this restriction will be lifted, but I haven't confirmed that yet.
Cheers
Rick