BBC News
image copyrightMet Police
image captionSaskia Jones, 23, and Jack Merritt, 25, were killed by Usman Khan during a conference on rehabilitating offenders
Three simple facts became crystal clear over the course of the inquests into the Fishmongers Hall terrorism attack, in which Jack Merritt and Saskia Jones died at the hand of Usman Khan.
Firstly, Khan, had entered and left prison as one of the most dangerous terrorism offenders of his generation.
Secondly, while counter-terrorism experts and investigators fully understood the threat he posed, some of the people directly interacting with Khan did not know all of those fears.
And thirdly, by the time Khan had decided to kill, nobody knew whether he was plotting or not - and so his trip went ahead without anyone being sure what risk he posed when he was allowed to travel to London alone.