SAGE? No one knows what they have been up to or how effective they have been. We will never be told anything other than they they are fabulous!
I think that WHO have done their best given the financial and legal limits they have. When you look at their announcements, they were on to it very early. There was talk about when they first used the word 'pandemic' but I took their caution in that, on previous occaisions, politicians have said they cried 'wolf'. Modern politicians will always spin it to suit themselves.