Don't get me wrong I have stuck with the rules in lockdown but I'm delighted that I didn't delete another app on my ancient phone to accommodate the rest and trace app.
My friend has just been told that he needs to self isolate for six days. On the day in question he went to a co-op with his brother who also has the app and that is it. His brother did not receive an alert and he did. He has also not been anywhere and needed to tag in well over a week.
This leaves the conclusion that it is pointless...He is isolated now but I don't see the point.