The link posted above about riots in Italy really frightens me.
Many cities, particularly London, are very densely populated with many people living in very small accomocation spaces including very high rise buildings with no balconies or outside space.
There is only so long humans will be able to tolerate a lock down.
If you think of the 2011 London riots (my layman's guess is) that involved two key groups - the initial rioters those reacting to the death of Mark Duggan and racist issues and then later criminal groups and similar to football hooliganism those who to be blunt fancied going rioting. These are small sectors and still the police lost control.
Here you have everyone locked up as it were, many many people kept as if under house arrest. Everyone. If you combine pressure cooker stress of extended lockdown, with fear of inability to eat, earn money have a roof over your head - the prospect of civil unrest is easy to see. But the potential for much larger scale rioting is huge.
You only have to watch what happened in India where a van was overturned by crowds to realise that if there is mass rioting, the police have no chance. There comes a point where the volume of people is no match.
I'm not a normally anxious person at all but the prospect of civil unrest on the horizon really frightens me.